Information recording medium, method for simultaneous recording and reproduction, and information recording and reproduction apparatus

ABSTRACT

In order to perform simultaneous recording and reproduction, a large capacity of buffer memories were required. In addition, it was difficult to record data while reproducing data which was recorded by a different apparatus. The present invention has an objective of providing an information recording medium, a simultaneous recording and reproduction method, and an information recording and reproduction apparatus which guarantee simultaneous recording and reproduction. The simultaneous recording and reproduction is guaranteed by reproducing data recorded in an area having at least a minimum size fulfilling the simultaneous recording and reproduction condition which allows for four access operations, recording data in an area having at least the same size, and performing reproduction and recording alternately by switching reproduction to recording when the data amount in the reproduction buffer becomes full and switching recording to reproduction when the data amount in the recording buffer becomes empty.

This application is a division of U.S. application Ser. No. 10/488,020filed Feb. 27, 2004 now U.S. Pat No. 7,233,553, the entire disclosure ofwhich is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to an information recording medium, amethod for simultaneous recording and reproduction, and an informationrecording and reproduction apparatus capable of simultaneous recordingand reproduction of a plurality of pieces of real time data.

BACKGROUND ART

One exemplary information recording medium having a sector structure isa hard disc. Hard discs, which are increasing more and more in memorycapacity and used for multimedia contents, are applied in wider fieldsincluding personal computers and various consumer apparatuses.

Hereinafter, simultaneous recording and reproduction in a conventionalhard disc will be described with reference to the figures. In harddiscs, the size of recording and reproduction areas is pre-fixed to be aunit larger than a sector, and access is performed in units offixed-size block.

FIG. 2 shows a model for simultaneously recording and reproducing aplurality of pieces of real time data. This model includes a pickup 74for recording real time data to and reproducing real time data from aninformation recording medium, an encoder 70 for encoding first real timedata, a recording buffer 72 for temporarily storing the encoded firstreal time data before the first real time data is recorded by the pickup74, a reproduction buffer 73 for temporarily storing second real timedata which is reproduced by the pickup 74, and a decoder 71 for decodingthe second real time data which is transferred from the reproductionbuffer 73.

FIG. 30 shows an example in which two pieces of real time data aresimultaneously recorded and reproduced while ensuring continuity usingthe recording buffer 72 and the reproduction buffer 73. In this example,while the first real time data is recorded in areas 81 and 84 of aninformation recording medium, the second real time data which isrecorded in areas 83 and 85 of the information recording medium isreproduced.

In FIG. 30, A81, A82 and A83 refer to operations of the pickup 74 ofmoving between areas to be accessed (access operations). It is assumedhere that the time required for each of the access operations A81, A82and A83 is a time period required for the pickup 74 to move between aninnermost area and an outermost area of the information recording medium(i.e., the maximum access time Ta). It is also assumed that the datatransfer rate between the pickup 74 and the recording buffer 72 and thedata transfer rate between the pickup 74 and the reproduction buffer 73are a constant rate Vt. It is also assumed that the data transfer ratebetween the encoder 70 and the recording buffer 72 and the data transferrate between the decoder 71 and the reproduction buffer 73 are aconstant rate Vd. In the case where the data to be recorded andreproduced is compressed at a variable rate, Vd is the maximum value ofthe range in which the rate is variable.

In a recording operation W81, data accumulated in the recording buffer72 is all recorded in the area 81. Then, data is accumulated in therecording buffer 72 during the access operation A81, a reproductionoperation R81 and the access operation A82. In a recording operationW82, data accumulated in the recording buffer 72 is all recorded in thearea 84. Then, data is accumulated in the recording buffer 72 during theaccess operation A83, a reproduction operation R82 and the next accessoperation (not shown).

During the recording operation W81 and the access operation A81, dataaccumulated in the reproduction buffer 73 is consumed, and data isaccumulated in the reproduction buffer 73 during the reproductionoperation R81. Then, during the access operation A82, the recordingoperation W82 and the access operation A83, data accumulated in thereproduction buffer 73 is consumed, and data is accumulated in thereproduction buffer 73 during the reproduction operation R82.

In the case where the transfer rate of the data to be recorded and thetransfer rate of the data to be reproduced are each constant, the dataamount in the recording buffer 72 is balanced between a recording stateand a non-recording state. The data amount in the reproduction buffer 73is also balanced between a reproduction state and a non-reproductionstate. Since the recording of the first real time data and thereproduction of the second real time data are performed alternately, thetwo pieces of real time data can be recorded and reproducedcontinuously.

The example shown in FIG. 30 shows a condition for the minimum size ofthe areas in which data can be recorded and reproduced. Namely, since itcannot be defined where in the information recording medium (disc) theareas for recording and reproduction exist, the access between therecording area and the reproduction area is considered based on themaximum access time including the time period until the rotation rate ofthe disc becomes a desired value.

FIG. 31 shows a transition in the data amount in the recording buffer 72and the reproduction buffer 73 while the data is recorded and reproducedat a variable rate. In the case where data of more than or equal to thesize of the recording area is not accumulated in the recording buffer 72at the time of termination of a series of operations of: a recordingoperation W91, an access operation A91, a reproduction operation R91 andan access operation A92; a low recording rate results in the state wherethere is no sufficient data to be recorded. Thus, the recordingoperation is temporarily interrupted, which extends the time requiredfor recording. In this case, an access operation A93 is performed foraccessing an area next to the area in which real time data has beenrecorded, and thus a reproduction operation R92 is performed. In thecase as described above where the data is recorded and access isperformed, both in units of fixed-size block, the memory size requiredfor the recording buffer 72 is a sum of the amount of data accumulatedduring the two access operations and one reproduction operation and thesize of the fixed block. The reproduction buffer 73 needs to have thesame memory size as that of the recording buffer 72.

In the case of a hard disc, data transfer capability is high. Therefore,the size of the fixed block can be reduced and the size of the buffermemory can also be reduced.

However, when the above-described system of simultaneous recording andreproduction is applied to an optical disc, there is a problem in that alarge buffer memory is necessary. The reasons are that the data transferrate of the optical disc is low and the access time is long. In order toperform simultaneous recording and reproduction for a disc having datarecorded thereon by a different apparatus, there is another problem thatcompatibility needs to be ensured for stable simultaneous recording andreproduction.

DISCLOSURE OF THE INVENTION

A method according to the present invention is for simultaneouslyrecording and reproducing a plurality of pieces of real time data inaccordance with a simultaneous recording and reproduction model. Thesimultaneous recording and reproduction model includes a pickup P foraccessing an area on an information recording medium, an encoding moduleEMi for encoding real time data Di, a recording buffer WBi foraccumulating the encoded real time data Di, a reproduction buffer RBjfor accumulating real time data Dj read from the information recordingmedium, and a decoding module DMj for decoding the real time data Djaccumulated in the reproduction buffer RBj. The method includes thesteps of searching for an unassigned area in a volume space in theinformation recording medium and assigning at least one unassigned areain the volume space as an area Ai in which the real time data Di is tobe recorded; executing a recording operation Wi for recording the realtime data Di accumulated in the recording buffer WBi in the area Ai;executing a reproduction operation Rj for reading the real time data Djfrom an area Aj having the real time data Dj recorded therein;determining whether the recording buffer WBi is empty or not while therecording operation Wi is being executed; when the recording buffer WBiis determined to be empty, switching the recording operation Wi toanother recording operation Wi or a reproduction operation Rj; and whenthe recording buffer WBi is determined not to be empty, continuing therecording operation Wi; and determining whether the reproduction bufferRBj is full or not while the reproduction operation Rj is beingexecuted; when the reproduction buffer RBj is determined to be full,switching the reproduction operation Rj to another reproductionoperation Rj or a recording operation Wi; and when the reproductionbuffer RBj is determined not to be full, continuing the reproductionoperation Rj. Each of the at least one area assigned as the area Ai isstructured to fulfill a condition that the recording buffer WBi can bemade empty by at most one access operation and at most two recordingoperations. Each of the at least one area assigned as the area Aj isstructured to fulfill a condition that the reproduction buffer RBj canbe made full by at most one access operation and at most tworeproduction operations. i is any integer of 1 or greater and m or less,j is any integer of (m+1) or greater and n or less, m is any integerwhich fulfills m<n and is 1 or greater, and n is any integer of 2 orgreater which represents the number of the plurality of pieces of realtime data for simultaneous recording and reproduction.

Each of at least one area assigned as the area Ai has a size of Y orgreater, and each of the at least one area assigned as the area Aj has asize of Y or greater. Y=2×n×Ta×Vd×Vt÷(Vt−n×Vd). Ta is an access timerequired for the pickup P to access between an innermost area and anoutermost area of the information recording medium. Vt is a datatransfer rate between the pickup P and the recording buffer WBi, andalso a data transfer rate between the pickup P and the reproductionbuffer RBj. Vd is a data transfer rate between the encoding module EMiand the recording buffer WBi, and also a data transfer rate between thedecoding module DMj and the reproduction buffer RBj, for all values of iand j.

Each of the at least one area assigned as the area Ai has a size of Yior greater, and each of the at least one area assigned as the area Ajhas a size of Yj or greater. Yi=(2×n×Ta×Vt×Vdi)÷{Vt−(Vd1+Vd2+ . . .+Vdn)}; and Yj=(2×n×Ta×Vt×Vdj)÷{Vt−(Vd1+Vd2+ . . . Vdn)}. Ta is anaccess time required for the pickup P to access between an innermostarea and an outermost area of the information recording medium. Vt is adata transfer rate between the pickup P and the recording buffer WBi,and also a data transfer rate between the pickup P and the reproductionbuffer RBj. Vdi is a data transfer rate between the encoding module EMiand the recording buffer WBi. Vdj is a data transfer rate between thedecoding module DMj and the reproduction buffer RBj.

The method further includes the steps of estimating a first access timerequired for the pickup P to access from an area Ak to an area Al and asecond access time required for the pickup P to access from one areaamong at least one area assigned as the area Ak to another area, where kand 1 are each any integer of 1 or greater and n or less, and k≠1.

Each of the at least one area assigned as the area Ai has a size of Y orgreater, and each of the at least one area assigned as the area Aj has asize of Y or greater. Y={2×(T1+ . . . +Tn)×Vt×Vd}÷(Vt−n×Vd). Tk is thefirst access time or the second access time. Vt is a data transfer ratebetween the pickup P and the recording buffer WBi, and also a datatransfer rate between the pickup P and the reproduction buffer RBj. Vdis a data transfer rate between the encoding module EMi and therecording buffer WBi, and also a data transfer rate between the decodingmodule DMj and the reproduction buffer RBj, for all values of i and j.

Each of the at least one area assigned as the area Ai has a size of Yior greater, and each of the at least one area assigned as the area Ajhas a size of Yj or greater. Yi={2×(T1+ . . . +Tn)×Vt×Vdi}÷{Vt−(Vd1+Vd2+. . . +Vdn)}; and Yj={2×(T1+ . . . +Tn)×Vt×Vdj}÷{Vt−(Vd1+Vd2+ . . .+Vdn)}. Tk is the first access time or the second access time. Vt is adata transfer rate between the pickup P and the recording buffer WBi,and also a data transfer rate between the pickup P and the reproductionbuffer RBj. Vdi is a data transfer rate between the encoding module EMiand the recording buffer WBi. Vdj is a data transfer rate between thedecoding module DMj and the reproduction buffer RBj.

The area Ai and the area Aj are provided in an outer portion of theinformation recording medium, for all values of i and for all values ofj.

A method according to the present invention is for simultaneouslyrecording and reproducing a plurality of pieces of real time data inaccordance with a simultaneous recording and reproduction model. Thesimultaneous recording and reproduction model includes a pickup P foraccessing an area on an information recording medium, an encoding moduleEMi for encoding real time data Di, a recording buffer WBi foraccumulating the encoded real time data Di, a reproduction buffer RBjfor accumulating real time data Dj read from the information recordingmedium, and a decoding module DMj for decoding the real time data Djaccumulated in the reproduction buffer RBj. The method includes thesteps of searching for an unassigned area in a volume space in theinformation recording medium and assigning at least one unassigned areain the volume space as an area Ai in which the real time data Di is tobe recorded; executing a recording operation Wi for recording the realtime data Di accumulated in the recording buffer WBi in the area Ai;executing a reproduction operation Rj for reading the real time data Djfrom an area Aj having the real time data Dj recorded therein;determining whether the real time data Di has been recorded up to an endof one of at least one area assigned as the area Ai or not in therecording operation Wi; when the real time data Di is determined to havebeen recorded up to the end, switching the recording operation Wi toanother recording operation Wi or a reproduction operation Rj; and whenthe real time data Di is determined not to have been recorded up to theend, continuing the recording operation Wi; and determining whether thereal time data Dj has been reproduced up to an end of one of at leastone area assigned as the area Aj or not in the reproduction operationRj; when the real time data Dj is determined to have been reproduced upto the end, switching the reproduction operation Rj to anotherreproduction operation Rj or a recording operation Wi; and when the realtime data Dj is determined not to have been reproduced up to the end,continuing the reproduction operation Rj. Each of the at least one areaassigned as the area Ai is structured to fulfill a condition that thereal time data Di, which is accumulated in the recording buffer WBiduring n number of access operations accompanying switching between therecording operation and the reproduction operation, (m−1) number ofrecording operations and (n−m) number of reproduction operations, can berecorded by one recording operation. Each of the at least one areaassigned as the area Aj is structured to fulfill a condition that thereal time data Dj, which is accumulated in the reproduction buffer RBjduring one reproduction operation, can be consumed during n number ofaccess operations accompanying switching between the reproductionoperation and the recording operation, (n−m−1) number of reproductionoperations and m number of recording operations. i is any integer of 1or greater and m or less, j is any integer of (m+1) or greater and n orless, m is any integer which fulfills m<n and is 1 or greater, and n isany integer of 2 or greater which represents the number of the pluralityof pieces of real time data for simultaneous recording and reproduction.

Each of at least one area assigned as the area Ai has a size of Yi, andeach of the at least one area assigned as the area Aj has a size of Yj.Yi=(n×Ta×Vt×Vdi)÷{Vt−(Vd1+Vd2+ . . . +Vdn)}; andYj=(n×Ta×Vt×Vdj)÷{Vt−(Vd1+Vd2+ . . . +Vdn)}. Ta is an access timerequired for the pickup P to access between an innermost area and anoutermost area of the information recording medium. Vt is a datatransfer rate between the pickup P and the recording buffer WBi, andalso a data transfer rate between the pickup P and the reproductionbuffer RBj. Vdi is a data transfer rate between the encoding module EMiand the recording buffer WBi. Vdj is a data transfer rate between thedecoding module DMj and the reproduction buffer RBj.

The method further includes the steps of estimating an access timerequired for the pickup P to access from an area Ak to an area Al wherek and 1 are each any integer of 1 or greater and n or less, and k≠1.

Each of the at least one area assigned as the area Ai has a size of Y,and each of the at least one area assigned as the area Aj has a size ofY. Y={(T1+ . . . +Tn)×Vt×Vd}÷(Vt−n×Vd). Tk is the access time. Vt is adata transfer rate between the pickup P and the recording buffer WBi,and also a data transfer rate between the pickup P and the reproductionbuffer RBj. Vd is a data transfer rate between the encoding module EMiand the recording buffer WBi, and also a data transfer rate between thedecoding module DMj and the reproduction buffer RBj, for all values of iand j.

Each of the at least one area assigned as the area Ai has a size of Yi,and each of the at least one area assigned as the area Aj has a size ofYj. Yi={(T1+ . . . +Tn)×Vt×Vdi}÷{Vt−(Vd1+Vd2+ . . . +Vdn)}; and Yj={(T1+. . . +Tn)×Vt×Vdj}÷{Vt−(Vd1+Vd2+ . . . +Vdn)}. Tk is the access time. Vtis a data transfer rate between the pickup P and the recording bufferWBi, and also a data transfer rate between the pickup P and thereproduction buffer RBj. Vdi is a data transfer rate between theencoding module EMi and the recording buffer WBi. Vdj is a data transferrate between the decoding module DMj and the reproduction buffer RBj.

The area Ai and the area Aj are provided in an outer portion of theinformation recording medium, for all values of i and for all values ofj.

An information recording and reproduction apparatus according to thepresent invention is for simultaneously recording and reproducing aplurality of pieces of real time data in accordance with a simultaneousrecording and reproduction model. The simultaneous recording andreproduction model includes a pickup P for accessing an area on aninformation recording medium, an encoding module EMi for encoding realtime data Di, a recording buffer WBi for accumulating the encoded realtime data Di, a reproduction buffer RBj for accumulating real time dataDj read from the information recording medium, and a decoding module DMjfor decoding the real time data Dj accumulated in the reproductionbuffer RBj. The information recording and reproduction apparatusincludes means for searching for an unassigned area in a volume space inthe information recording medium and assigning at least one unassignedarea in the volume space as an area Ai in which the real time data Di isto be recorded; means for executing a recording operation Wi forrecording the real time data Di accumulated in the recording buffer WBiin the area Ai; means for executing a reproduction operation Rj forreading the real time data Dj from an area Aj having the real time dataDj recorded therein; means for determining whether the recording bufferWBi is empty or not while the recording operation Wi is being executed;when the recording buffer WBi is determined to be empty, switching therecording operation Wi to another recording operation Wi or areproduction operation Rj; and when the recording buffer WBi isdetermined not to be empty, continuing the recording operation Wi; andmeans for determining whether the reproduction buffer RBj is full or notwhile the reproduction operation Rj is being executed; when thereproduction buffer RBj is determined to be full, switching thereproduction operation Rj to another reproduction operation Rj or arecording operation Wi; and when the reproduction buffer RBj isdetermined not to be full, continuing the reproduction operation Rj.Each of the at least one area assigned as the area Ai is structured tofulfill a condition that the recording buffer WBi can be made empty byat most one access operation and at most two recording operations. Eachof the at least one area assigned as the area Aj is structured tofulfill a condition that the reproduction buffer RBj can be made full byat most one access operation and at most two reproduction operations. iis any integer of 1 or greater and m or less, j is any integer of (m+1)or greater and n or less, m is any integer which fulfills m<n and is 1or greater, and n is any integer of 2 or greater which represents thenumber of the plurality of pieces of real time data for simultaneousrecording and reproduction.

An information recording and reproduction apparatus according to thepresent invention is for simultaneously recording and reproducing aplurality of pieces of real time data in accordance with a simultaneousrecording and reproduction model. The simultaneous recording andreproduction model includes a pickup P for accessing an area on aninformation recording medium, an encoding module EMi for encoding realtime data Di, a recording buffer WBi for accumulating the encoded realtime data Di, a reproduction buffer RBj for accumulating real time dataDj read from the information recording medium, and a decoding module DMjfor decoding the real time data Dj accumulated in the reproductionbuffer RBj. The information recording and reproduction apparatusincludes means for searching for an unassigned area in a volume space inthe information recording medium and assigning at least one unassignedarea in the volume space as an area Ai in which the real time data Di isto be recorded; means for executing a recording operation Wi forrecording the real time data Di accumulated in the recording buffer WBiin the area Ai; means for executing a reproduction operation Rj forreading the real time data Dj from an area Aj having the real time dataDj recorded therein; means for determining whether the real time data Dihas been recorded up to an end of one of at least one area assigned asthe area Ai or not in the recording operation Wi; when the real timedata Di is determined to have been recorded up to the end, switching therecording operation Wi to another recording operation Wi or areproduction operation Rj; and when the real time data Di is determinednot to have been recorded up to the end, continuing the recordingoperation Wi; and means for determining whether the real time data Djhas been reproduced up to an end of one of at least one area assigned asthe area Aj or not in the reproduction operation Rj; when the real timedata Dj is determined to have been reproduced up to the end, switchingthe reproduction operation Rj to another reproduction operation Rj or arecording operation Wi; and when the real time data Dj is determined notto have been reproduced up to the end, continuing the reproductionoperation Rj. Each of the at least one area assigned as the area Ai isstructured to fulfill a condition that the real time data Di, which isaccumulated in the recording buffer WBi during n number of accessoperations accompanying switching between the recording operation andthe reproduction operation, (m−1) number of recording operations and(n−m) number of reproduction operations, can be recorded by onerecording operation. Each of the at least one area assigned as the areaAj is structured to fulfill a condition that the real time data Dj,which is accumulated in the reproduction buffer RBj during onereproduction operation, can be consumed during n number of accessoperations accompanying switching between the reproduction operation andthe recording operation, (n−m−1) number of reproduction operations and mnumber of recording operations. i is any integer of 1 or greater and mor less, j is any integer of (m+1) or greater and n or less, m is anyinteger which fulfills m<n and is 1 or greater, and n is any integer of2 or greater which represents the number of the plurality of pieces ofreal time data for simultaneous recording and reproduction.

An information recording medium according to the present inventionallows for simultaneous recording and reproducing of a plurality ofpieces of real time data in accordance with a simultaneous recording andreproduction model. The simultaneous recording and reproduction modelincludes a pickup P for accessing an area on the information recordingmedium, an encoding module EMi for encoding real time data Di, arecording buffer WBi for accumulating the encoded real time data Di, areproduction buffer RBj for accumulating real time data Dj read from theinformation recording medium, and a decoding module DMj for decoding thereal time data Dj accumulated in the reproduction buffer RBj. Each of atleast one area assigned as an area Ai in which the real time data Di isto be recorded is structured to fulfill a condition that the recordingbuffer WBi can be made empty by at most one access operation and at mosttwo recording operations. Each of at least one area assigned as an areaAj having the real time data Dj recorded therein is structured tofulfill a condition that the reproduction buffer RBj can be made full byat most one access operation and at most two reproduction operations. iis any integer of 1 or greater and m or less, j is any integer of (m+1)or greater and n or less, m is any integer which fulfills m<n and is 1or greater, and n is any integer of 2 or greater which represents thenumber of the plurality of pieces of real time data for simultaneousrecording and reproduction.

Each of the at least one area assigned as the area Ai has a size of Y orgreater, and each of the at least one area assigned as the area Aj has asize of Y or greater. Y=2×n×Ta×Vd×Vt÷(Vt−n×Vd). Ta is an access timerequired for the pickup P to access between an innermost area and anoutermost area of the information recording medium. Vt is a datatransfer rate between the pickup P and the recording buffer WBi, andalso a data transfer rate between the pickup P and the reproductionbuffer RBj. Vd is a data transfer rate between the encoding module EMiand the recording buffer WBi, and also a data transfer rate between thedecoding module DMj and the reproduction buffer RBj, for all values of iand j.

Each of the at least one area assigned as the area Ai has a size of Yior greater, and each of the at least one area assigned as the area Ajhas a size of Yj or greater. Yi=(2×n×Ta×Vt×Vdi)÷{Vt−(Vd1+Vd2+ . . .+Vdn)}; and Yj=(2×n×Ta×Vt×Vdj)÷{Vt−(Vd1+Vd2+ . . . +Vdn)}. Ta is anaccess time required for the pickup P to access between an innermostarea and an outermost area of the information recording medium. Vt is adata transfer rate between the pickup P and the recording buffer WBi,and also a data transfer rate between the pickup P and the reproductionbuffer RBj. Vdi is a data transfer rate between the encoding module EMiand the recording buffer WBi. Vdj is a data transfer rate between thedecoding module DMj and the reproduction buffer RBj.

Each of the at least one area assigned as the area Ai has a size of Y orgreater, and each of the at least one area assigned as the area Aj has asize of Y or greater. Y={2×(T1+ . . . +Tn)×Vt×Vd}÷(Vt−n×Vd). Tk is anestimated first access time required for the pickup P to access from anarea Ak to an area Al or an estimated second access time required forthe pickup P to access from one area among at least one area assigned asthe area Ak to another area, where k and 1 are each any integer of 1 orgreater and n or less, and k≠1. Vt is a data transfer rate between thepickup P and the recording buffer WBi, and also a data transfer ratebetween the pickup P and the reproduction buffer RBj. Vd is a datatransfer rate between the encoding module EMi and the recording bufferWBi, and also a data transfer rate between the decoding module DMj andthe reproduction buffer RBj, for all values of i and

Each of the at least one area assigned as the area Ai has a size of Yior greater, and each of the at least one area assigned as the area Ajhas a size of Yj or greater. Yi={2×(T1+ . . . +Tn)×Vt×Vdi}÷{Vt−(Vd1+Vd2+. . . +Vdn)}; and Yj={2×(T1+ . . . +Tn)×Vt×Vdj}÷{Vt−(Vd1+Vd2+ . . .+Vdn)}. Tk is an estimated first access time required for the pickup Pto access from an area Ak to an area Al or an estimated second accesstime required for the pickup P to access from one area among at leastone area assigned as the area Ak to another area, where k and 1 are eachany integer of 1 or greater and n or less, and k≠1. Vt is a datatransfer rate between the pickup P and the recording buffer WBi, andalso a data transfer rate between the pickup P and the reproductionbuffer RBj. Vdi is a data transfer rate between the encoding module EMiand the recording buffer WBi. Vdj is a data transfer rate between thedecoding module DMj and the reproduction buffer RBj.

The area Ai and the area Aj are provided in an outer portion of theinformation recording medium, for all values of i and for all values ofj.

An information recording medium according to the present inventionallows for simultaneous recording and reproducing of a plurality ofpieces of real time data in accordance with a simultaneous recording andreproduction model. The simultaneous recording and reproduction modelincludes a pickup P for accessing an area on the information recordingmedium, an encoding module EMi for encoding real time data Di, arecording buffer WBi for accumulating the encoded real time data Di, areproduction buffer RBj for accumulating real time data Dj read from theinformation recording medium, and a decoding module DMj for decoding thereal time data Dj accumulated in the reproduction buffer RBj. Each of atleast one area assigned as an area Ai in which the real time data Di isto be recorded is structured to fulfill a condition that the real timedata Di, which is accumulated in the recording buffer WBi during nnumber of access operations accompanying switching between the recordingoperation and the reproduction operation, (m−1) number of recordingoperations and (n−m) number of reproduction operations, can be recordedby one recording operation. Each of at least one area assigned as anarea Aj having the real time data Dj recorded therein is structured tofulfill a condition that the real time data Dj, which is accumulated inthe reproduction buffer RBj during one reproduction operation, can beconsumed during n number of access operations accompanying switchingbetween the reproduction operation and the recording operation, (n−m−1)number of reproduction operations and m number of recording operations.i is any integer of 1 or greater and m or less, j is any integer of(m+1) or greater and n or less, m is any integer which fulfills m<n andis 1 or greater, and n is any integer of 2 or greater which representsthe number of the plurality of pieces of real time data for simultaneousrecording and reproduction.

Each of the at least one area assigned as the area Ai has a size of Yi,and each of the at least one area assigned as the area Aj has a size ofYj. Yi=(n×Ta×Vt×Vdi)÷{Vt−(Vd1+Vd2+ . . . +Vdn)}; andYj=(n×Ta×Vt×Vdj)÷{Vt−(Vd1+Vd2+ . . . +Vdn)}. Ta is an access timerequired for the pickup P to access between an innermost area and anoutermost area of the information recording medium. Vt is a datatransfer rate between the pickup P and the recording buffer WBi, andalso a data transfer rate between the pickup P and the reproductionbuffer RBj. Vdi is a data transfer rate between the encoding module EMiand the recording buffer WBi. Vdj is a data transfer rate between thedecoding module DMj and the reproduction buffer RBj.

Each of the at least one area assigned as the area Ai has a size of Y,and each of the at least one area assigned as the area Aj has a size ofY. Y={(T1+ . . . +Tn)×Vt×Vd}÷(Vt−n×Vd). Tk is an estimated access timerequired for the pickup P to access from an area Ak to an area Al, wherek and 1 are each any integer of 1 or greater and n or less, and k≠1. Vtis a data transfer rate between the pickup P and the recording bufferWBi, and also a data transfer rate between the pickup P and thereproduction buffer RBj. Vd is a data transfer rate between the encodingmodule EMi and the recording buffer WBi, and also a data transfer ratebetween the decoding module DMj and the reproduction buffer RBj, for allvalues of i and j.

Each of the at least one area assigned as the area Ai has a size of Yi,and each of the at least one area assigned as the area Aj has a size ofYj. Yi={(T1+ . . . +Tn)×Vt×Vdi}÷{Vt−(Vd1+Vd2+ . . . +Vdn)}; and Yj={(T1+. . . +Tn)×Vt×Vdj}÷{Vt−(Vd1+Vd2+ . . . +Vdn)}. Tk is an estimated accesstime required for the pickup P to access from an area Ak to an area Al,where k and 1 are each any integer of 1 or greater and n or less, andk≠1. Vt is a data transfer rate between the pickup P and the recordingbuffer WBi, and also a data transfer rate between the pickup P and thereproduction buffer RBj. Vdi is a data transfer rate between theencoding module EMi and the recording buffer WBi. Vdj is a data transferrate between the decoding module DMj and the reproduction buffer RBj.

The area Ai and the area Aj are provided in an outer portion of theinformation recording medium, for all values of i and for all values ofj.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a simultaneous recording and reproduction condition for aninformation recording medium according to a first example of the presentinvention.

FIG. 2 shows a simultaneous recording and reproduction model.

FIG. 3 shows a layout illustrating access operations on the informationrecording medium according to the first example of the presentinvention.

FIG. 4 shows a switching operation for simultaneous recording andreproduction to and from the information recording medium according tothe first example of the present invention.

FIG. 5 is a block diagram illustrating an information recording andreproduction apparatus according to the first example of the presentinvention.

FIG. 6 is a flowchart illustrating a method for simultaneous recordingand reproduction according to the first example of the presentinvention.

FIG. 7 shows a directory structure of data to be recorded.

FIG. 8 shows an operation for skip recording.

FIG. 9 shows recording operations, reproduction operations and accessoperations for simultaneous recording and reproduction of two pieces ofreal time data according to a second example of the present invention.

FIG. 10 shows a layout of reproduction areas and recording areas on thedisc according to the second example of the present invention.

FIG. 11 shows recording operations, reproduction operations and accessoperations for simultaneous recording and reproduction of three piecesof real time data according to the second example of the presentinvention.

FIG. 12 shows recording operations, reproduction operations and accessoperations for simultaneous recording and reproduction of two pieces ofreal time data according to a third example of the present invention.

FIG. 13 shows recording operations, reproduction operations and accessoperations for simultaneous recording and reproduction of three piecesof real time data according to the third example of the presentinvention.

FIG. 14 shows the details of the access time according to the thirdexample of the present invention.

FIG. 15 shows the relationship between the rotation rate difference andthe access time of the disc according to the third example of thepresent invention.

FIG. 16 shows the relationship between the radial position and therotation rate difference of the disc according to the third example ofthe present invention.

FIG. 17 shows an arrangement of recording areas in the case where AVMdata and data for after-recording (post-recording) are recordedalternately according to a fourth example of the present invention.

FIG. 18 shows access operations for recording and reproduction withafter-recording in the case where AVM data and data for after-recordingare recorded alternately according to the fourth example of the presentinvention.

FIG. 19 shows access operations for reproduction after after-recordingin the case where AVM data and data for after-recording are recordedalternately according to the fourth example of the present invention.

FIG. 20 is an arrangement of recording areas in the case where AVM dataand data for after-recording are recorded in areas distanced from eachother according to the fourth example of the present invention.

FIG. 21 shows access operations for recording and reproduction withafter-recording in the case where AVM data and data for after-recordingare recorded in areas distanced from each other according to the fourthexample of the present invention.

FIG. 22 shows access operations for reproduction after after-recordingin the case where AVM data and data for after-recording are recorded inareas distanced from each other according to the fourth example of thepresent invention.

FIG. 23 shows an arrangement of recording areas in the case where audiodata, video data and data for after-recording are recorded in separateareas according to the fourth example of the present invention.

FIG. 24 shows access operations for recording and reproduction withafter-recording in the case where audio data, video data and data forafter-recording are recorded in separate areas according to the fourthexample of the present invention.

FIG. 25 shows access operations for reproduction after after-recordingin the case where audio data, video data and data for after-recordingare recorded in separate areas according to the fourth example of thepresent invention.

FIG. 26 shows access operations and a layout of recording areas forsimultaneous recording and reproduction of three pieces of real timedata according to the third example of the present invention.

FIG. 27 is a flowchart illustrating a method for simultaneous recordingand reproduction according to the third example of the presentinvention.

FIG. 28 shows a layout of recording areas for simultaneous recording andreproduction of two pieces of real time data according to the thirdexample of the present invention.

FIG. 29 shows areas to be accessed on the disc and an access timerequired for full seek in the area according to the third example of thepresent invention.

FIG. 30 shows a conventional simultaneous recording and reproductioncondition.

FIG. 31 shows a conventional simultaneous recording and reproductionoperation.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described byway of drawings.

EXAMPLE 1

A method for performing simultaneous recording and reproduction of aplurality of pieces of real time data using a simultaneous recording andreproduction model will be described. The simultaneous recording andreproduction model used here has the identical structure to that of thesimultaneous recording and reproduction model shown in FIG. 2 in thattwo buffers, i.e., the recording buffer 72 and the reproduction buffer73 are included. The term “real time data” refers to data including atleast either video data or audio data. The term “information recordingmedium” refers to any type of recording medium such as, for example, anoptical disc.

FIG. 1 shows a transition in the data amounts in the recording buffer 72and the reproduction buffer 73 in the simultaneous recording andreproduction model during simultaneous recording and reproduction ofreal time data A and B.

In the example shown in FIG. 1, while the real time data A is recordedin areas 1, 2, 3 and 4 of an information recording medium, real timedata B recorded in areas 5, 6, 7 and 8 of the information recordingmedium is reproduced. The areas 1, 2, 3 and 4 are assigned as areas inwhich the real time data A is to be recorded. The areas 5, 6, 7 and 8are assigned as areas having the real time data B recorded therein.

In FIG. 1, A1 through A7 refer to operations of the pickup 74 of movingbetween areas to be accessed (access operations). It is assumed herethat the time required for each of the access operations A1 through A7is a time period required for the pickup 74 to move between an innermostarea and an outermost area of the information recording medium (i.e.,the maximum access time Ta). It is also assumed that the data transferrate between the pickup 74 and the recording buffer 72 and the datatransfer rate between the pickup 74 and the reproduction buffer 73 are aconstant rate Vt. It is also assumed that the data transfer rate betweenthe encoder 70 and the recording buffer 72 and the data transfer ratebetween the decoder 71 and the reproduction buffer 73 are a constantrate Vd. In the case where the data to be recorded and reproduced iscompressed at a variable rate, Vd is the maximum value of the range inwhich the rate is variable.

In a recording operation W1, real time data A accumulated in therecording buffer 72 is recorded in the area 1. When the real time data Ais recorded to the end of the area 1, the recording buffer 72 is notempty. Therefore, the recording operation of the real time data A is notswitched to the reproduction operation of real time data B. After anaccess operation A1, in a recording operation W2, real time data Aaccumulated in the recording buffer 72 is recorded in the area 2.

While the recording operation W2 is being executed, the recording buffer72 becomes empty. As a result, the recording operation of the real timedata A is switched to the reproduction operation of the real time data B(access operation A2).

In a reproduction operation R1, the real time data B is read from thearea 5 and accumulated in the reproduction buffer 73. When the data isreproduced from the end of the area 5, the reproduction buffer 73 is notfull. Therefore, the reproduction operation of the real time data B isnot switched to the recording operation of the real time data A. Afteran access operation A3, in a reproduction operation R2, the real timedata B is read from the area 6 and accumulated in the reproductionbuffer 73.

While the reproduction operation R2 is being executed, the reproductionbuffer 73 becomes full. As a result, the reproduction operation of thereal time data B is switched to the recording operation of the real timedata A (access operation A4).

Thus, the method of simultaneous recording and reproduction according tothe present invention is designed so as to fulfill both (i) thecondition that the recording buffer 72 can be made empty by at most oneaccess operation and at most two recording operations and (ii) thecondition that the reproduction buffer 73 can be made full by at mostone access operation and at most two reproduction operations. Namely,the condition for simultaneous recording and reproduction is to fulfillthese two conditions. By fulfilling these two conditions, it is madepossible to surely record the real time data A on the informationrecording medium while reproducing the real time data B recorded on theinformation recording medium, without causing the recording buffer 72and the reproduction buffer 73 to overflow, and without causing therecording buffer 72 and the reproduction buffer 73 to underflow.

For example, the above-mentioned condition for simultaneous recordingand reproduction can be fulfilled where each of at least one areaassigned as an area in which the real time data A is to be recorded hasa size of Y or greater, and each of at least one area assigned as anarea having the real time data B recorded therein has a size of Y orgreater. Accordingly, the condition for simultaneous recording andreproduction can be fulfilled by searching for at least one unassignedarea having a size of Y or greater and assigning the at least one areathus found as an area in which the real time data A is to be recorded.The area for the real time data B is obtained in a similar manner.

In the example shown in FIG. 1, the condition for simultaneous recordingand reproduction can be fulfilled where each of the areas 1, 2, 3 and 4has a size of Y or greater, and each of the areas 5, 6, 7 and 8 has asize of Y or greater.

The minimum size Y for each of the recording area and the reproductionarea, and a buffer size B which is required for each of the recordingbuffer 72 and the reproduction buffer 73, are obtained by the followingexpressions.Y=4×Ta×Vd×Vt÷(Vt−2×Vd)B=(4×Ta+Y÷Vt)×Vd

The expression for obtaining the minimum size Y for each of therecording area and the reproduction area is derived as follows.

During a recording operation of the real time data A, the data in therecording buffer 72 is consumed at Vt−Vd. During an access operation anda reproduction operation of the real time data B, the data in therecording buffer 72 is accumulated at Vd. The data amount which isconsumed from the recording buffer 72 during the recording operation W1,the access operation A1 and the recording operation W2 is equal to thedata amount accumulated in the recording buffer 72 during the accessoperation A2, the reproduction operation R1, the access operation A3,the reproduction operation R2 and the access operation A4. Accordingly,for simultaneous recording and reproduction of two pieces of real timedata, the following expression is satisfied.Y÷Vt×(Vt−Vd)−Ta×Vd=(3×Ta+Y÷Vt)×Vd

By manipulating this expression, the above expression for obtaining theminimum size Y for each of the recording area and the reproduction areais obtained.

In the case where the number of pieces of real time data which are to besimultaneously recorded and reproduced is n (n is any integer of 2 orgreater), a simultaneous recording and reproduction model including mnumber of encoders, m number of recording buffers, (n−m) number ofdecoders, and (n−m) number of reproduction buffers is used. Here, m isany integer which fulfills m<n and is 1 or greater. In this case, thenumber of access operations is in proportion to the number of pieces ofreal time data to be simultaneously recorded and reproduced. Therefore,the following expression is satisfied.Y÷Vt×(Vt−Vd)−Ta×Vd=((2×n−1)×Ta+(n−1)×Y÷Vt)×Vd

Accordingly, when the number of pieces of real time data which are to besimultaneously recorded and reproduced is n, the minimum size Y for eachof the recording area and the reproduction area and the size B requiredfor each of the recording buffer and the reproduction buffer, areobtained by the following expressions.Y=2×n×Ta×Vd×Vt÷(Vt−n×Vd)B=(2×n×Ta+(n−1)×Y/Vt)×Vd

The number of pieces of data to be recorded may be different from thenumber of pieces of data to be reproduced. A recording operation may beswitched to another recording operation, or may be switched to areproduction operation. Similarly, a reproduction operation may beswitched to another reproduction operation, or may be switched to arecording operation. When the data transfer rate of the data to berecorded or reproduced is maximum, it is sufficient to record orreproduce n number of real time data, and there is clearly no limitationon the combination of the number of pieces of data to be recorded andthe number of pieces of data to be reproduced.

One of the differences of the present invention from the prior art forsimultaneous recording and reproduction of two pieces of real time datais that access is operated four times according to the presentinvention. According to the present invention, the access operation isperformed when the recording operation of real time data A and thereproduction operation of the real time data B are switched to eachother, and also when access is performed from one of at least one areaassigned as an area in which real time data A (or real time data B) isto be recorded to another area. Accordingly, the present inventionprovides a model capable of performing an access operation four timesfrom the time when recording buffer 72 becomes full until the next timewhen recording buffer 72 becomes full (or from the time whenreproduction buffer 73 becomes empty until the next time whenreproduction buffer 73 becomes empty). In this manner, it is madepossible to dynamically switch the recording operation and thereproduction operation to each other in accordance with the transitionin the data amounts in the recording buffer 72 and the reproductionbuffer 73. Thus, the transition in the data amounts in the recordingbuffer 72 and the reproduction buffer 73 can be stably controlled. Inmore detail, when the data amount in the recording buffer 72 becomesclose to full, the reproduction operation of the real time data B isimmediately switched to the recording operation of the real time data A.In this way, the data amount in the recording buffer 72 can bedecreased. When the data amount in the reproduction buffer 73 becomesclose to empty, the recording operation of the real time data A isimmediately switched to the reproduction operation of the real time dataB. In this way, the data amount in the reproduction buffer 73 can beincreased.

FIG. 3 shows an example of an arrangement of areas on an informationrecording medium (optical disc), in which files to be managed by avolume file structure defined by the ECMA167 Standards are recorded.

In FIG. 3, W1 through W4 refer to the recording operations describedabove with reference to FIG. 1, and R1 through R4 refer to thereproduction operations described above with reference to FIG. 1. A1through A7 refer to the access operations described above with referenceto FIG. 1.

In FIG. 3, the top side represents the inner side of the optical disc,and the bottom side represents the outer side of the optical disc. In avolume space, a volume structure area 11 and a file structure area 12are assigned. The file structure area 12 includes a space bit map 21 inwhich unused areas in the volume space are registered as unassignedareas sector by sector, and a data structure corresponding to thedirectory structure shown in FIG. 7 (i.e., a file entry 22 of a rootdirectory, a file identification descriptor 23 of FILE-A, a fileidentification descriptor 24 of FILE-B, a file entry 25 of FILE-A, and afile entry 26 of FILE-B).

According to the ECMA167 Standards, an area in which file data isrecorded is referred to as an “extent”. Positional information of theextent is registered in the file entry. For each file under thedirectory, a file identification descriptor is recorded in the filestructure area 12.

An area in which real time data is recorded is referred to as a “realtime extent” so as to be distinguished from the area where general datais recorded.

In the example shown in FIG. 3, as areas in which real time data ofFILE-A is to be recorded, recording areas 13, 14 and 15 in an innerportion of the optical disc are assigned. As areas having real time dataof FILE-B recorded therein, reproduction areas 16, 17 and 18 areassigned. The recording area 15 and the reproduction area 16 aredistanced from each other such that an access time required for accesstherebetween is equal to an access time required for access between aninnermost area and an outermost area of the optical disc.

Each of the recording areas 13 through 15 has a size of Y (minimum sizefor the recording area) or greater in order to fulfill theabove-described simultaneous recording and reproduction condition. Eachof the reproduction areas 16 through 18 has a size of Y (minimum sizefor the recording area) or greater in order to fulfill theabove-described simultaneous recording and reproduction condition. Thus,even when, for example, the real time data is actually recorded in apart of a recording area, the real time data can further be recorded inthe next recording area after the access operation. Therefore, the realtime data can be recorded in an area having a total size of Y orgreater. Under the condition for simultaneous recording and reproductiondescribed above with reference to FIG. 1, a time period required for theaccess operation (access time) is set to be an access time required foraccessing from an innermost area to an outermost area of the opticaldisc. Therefore, regardless of where in the optical disc the recordingarea and the reproduction area are located, simultaneous recording andreproduction can be guaranteed.

FIG. 4 shows a transition in the data amounts in the recording buffer 72and the reproduction buffer 73.

Hereinafter, with reference to FIG. 4, the relationship between (i) thetransition in the transfer rate of the data to be recorded andreproduced and (ii) the transition in the data amounts in the recordingbuffer 72 and the reproduction buffer 73 will be described.

The recording areas 30 and 31 are assigned as areas in which the realtime data A is to be recorded. The reproduction areas 35 and 36 areassigned as areas having the real time data B recorded therein. Therecording area 31 includes areas 32, 33 and 34. The reproduction area 36includes areas 37, 38 and 39.

In a recording operation of the real time data A, when the data transferrate to the recording buffer 72 is maximum, the recording buffer 72becomes empty at time t24 as a result of performing a recordingoperation W11, an access operation A11, and a recording operation W13.When the data transfer rate to the recording buffer 72 is lower than themaximum rate, the amount of data transferred from the encoder 70 to therecording buffer 72 is smaller. Therefore, the recording buffer 72becomes empty at time t23, which is earlier than time t24, as a resultof performing the recording operation W11, the access operation A11, anda recording operation W12. Namely, when the data transfer rate from theencoder 70 to the recording buffer 72 is lower, the recording buffer 72becomes empty earlier. When the recording operation of the real timedata A is switched to the reproduction operation of the real time data Bat time t23, the time until the reproduction operation of real time dataB is switched to the next recording operation is equal to or less thanthe sum of (i) a time period required for performing three accessoperations and (ii) a time period required for performing tworeproduction operations for reproducing data from two reproductionareas. Therefore, the recording buffer 72 is not overflowed. Even whenthe data having the maximum transfer rate needs to be recorded in thenext recording operation, that data can be recorded in an area having asize of Y which is obtained based on the simultaneous recording andreproduction condition.

In a reproduction operation of the real time data B also, when the datatransfer rate from the reproduction buffer 73 is maximum, data can beread from an area having a size of Y by one reproduction operation. Whenthe data transfer rate from the reproduction buffer 73 is maximum, thereproduction buffer 73 becomes full at time t29 as a result ofperforming a reproduction operation R11, an access operation A14, and areproduction operation R13. When the data transfer rate from thereproduction buffer 73 is lower than the maximum rate, the amount ofdata transferred from the reproduction buffer 73 to the decoder 71 issmaller. Therefore, the reproduction buffer 73 becomes full at time t28,which is earlier than time t29, as a result of performing thereproduction operation R11, the access operation A14, and a reproductionoperation R12. Namely, when the data transfer rate from the reproductionbuffer 73 to the decoder 71 is lower, the reproduction buffer 73 becomesfull earlier. When the reproduction operation of the real time data B isswitched to the recording operation of the real time data A at time t28,the time until the recording operation of real time data A is switchedto the next reproduction operation is equal to or less than the sum of(i) a time period required for performing three access operations and(ii) a time period required for performing two recording operations forrecording data to two recording areas. Therefore, the reproductionbuffer 73 is not underflowed. Even when the data having the maximumtransfer rate needs to be reproduced in the next reproduction operation,that data can be reproduced from an area having a size of Y which isobtained based on the simultaneous recording and reproduction condition.

Next, an information recording and reproduction apparatus and a methodfor performing simultaneous recording and reproduction according to afirst example of the present invention will be described with referenceto FIGS. 3, 5 and 6.

FIG. 5 shows a structure of the information recording and reproductionapparatus in the first example.

The information recording and reproduction apparatus includes a systemcontrol section 501, an I/O bus 521, an optical disc drive 531, inputmeans 532 for designating a recording mode or instructing the start ofsimultaneous recording and reproduction, a tuner 535 for receiving TVbroadcasting, an encoder 533 for encoding an audio/video signal selectedby the tuner 535, a decoder 534 for decoding audio/video data, and a TV536 for reproducing the audio/video signal.

The system control section 501 is realized by, for example, amicrocomputer and a memory. The elements included in the system controlsection 501 are realized by, for example, the microcomputer executingvarious programs. The memories included in the system control section501 are realized by, for example, areas of one memory being used fordifferent uses.

Recording and reproduction switching means 502 switches a recordingoperation and a reproduction operation to each other while checking thedata amounts in the buffer memories. Unassigned area search means 503searches for an area fulfilling the simultaneous recording andreproduction condition from unassigned areas in the volume space. Filestructure processing means 504 reads data from the file structure area12 and analyzes the file structure. Data recording means 505 instructsthe optical disc drive 531 to record data. Data reproduction means 506instructs the optical disc drive 531 to reproduce data.

An assigned area memory 507 temporarily stores positional information ofthe recordable area which is found by the unassigned area search means503. A file structure memory 508 is for temporarily storing the datawhich is read from the file structure area 12 in the buffer memories. Abit map memory 509 is for reducing the number of times of access to thedisc by storing the data which is read from the space bit map 21. Arecording buffer memory 510 and a reproduction buffer memory 511respectively correspond to the recording buffer 72 and the reproductionbuffer 73 of the simultaneous recording and reproduction model, and eachhas a buffer memory which is greater than or equal to the sizecalculated based on the simultaneous recording and reproductioncondition.

FIG. 6 shows a procedure of a method for simultaneous recording andreproduction. Such a method is stored, for example, in the form of aprogram in a memory in the system control section 501. Such a programcan be executed by the microcomputer in the system control section 501.

The user uses the input means 532 to input an instruction forsimultaneous recording and reproduction to the information recording andreproduction apparatus. In compliance with the instruction forsimultaneous recording and reproduction, the minimum size Y for therecording area is determined in accordance with the maximum transferrate of the data to be recorded. The method for obtaining the minimumsize Y for the recording area is as described with reference to FIG. 1(Y=4×Ta×Vd×Vt÷(Vt−2×Vd)).

When recording a specific program such as a movie or the like, the usersets the recording time. In this manner, a recording parameter isdetermined (step S601).

The unassigned area search means 503 searches for an unassigned areahaving a size of Y (minimum size for the recording area) or greaterwhich is obtained in step S601, for each piece of real time data to berecorded, based on the data stored in the bit map memory 509. When theuser sets the recording time, the unassigned area search means 503performs a search for unassigned areas in the volume space until the sumof the sizes of the unassigned areas is greater than or equal to thelogical product of the maximum rate and the recording time, and assignsat least one unassigned area in the volume space as an area in whichreal time data is to be recorded (step S602). Accordingly, each of atleast one area assigned as the area in which real time data is to berecorded has a size of Y or greater. Thus, the simultaneous recordingand reproduction condition can be fulfilled.

In FIG. 3, the recording areas 13, 14 and 15 are assigned as areas inwhich the real time data A is to be recorded. Each of the recordingareas 13, 14 and 15 has a size of Y or greater. The positionalinformation on the recording areas 13, 14 and 15 is stored in theassigned area memory 507.

The data recording means 505 instructs the optical disc drive 531 torecord the real time data A accumulated in the recording buffer memory510 on the optical disc, and transfers the real time data A to berecorded to the optical disc drive 531 (step S603).

In FIG. 3, the real time data A is recorded in a part of the recordingarea 13 in the recording operation W1. When it is determined that therecording operation is to be continued in step S605 described below, thereal time data A is recorded from the start of the recording area 14 inthe recording operation W2 after the access operation A1.

In FIG. 3, the real time data A is recorded from the middle of therecording area 13. In the case where the recording operation is startedfrom the recording area 13, the real time data A may be recorded fromthe start of the recording area 13.

When the user uses the input means 532 to input an instruction forterminating recording or reproduction to the information recording andreproduction apparatus, the recording and reproduction switching means502 terminates the recording operation or the reproduction operation(step S604).

The recording and reproduction switching means 502 determines whetherthe recording buffer memory 510 is empty or not. When the recordingbuffer memory 510 is determined to be empty, the recording andreproduction switching means 502 switches the recording operation of thereal time data A to the reproduction operation of the real time data B.When the recording buffer memory 510 is determined not to be empty, therecording and reproduction switching means 502 continues the recordingoperation of the real time data A (step S605).

In FIG. 3, the recording buffer memory 510 becomes empty in therecording operation W2. Thus, the recording operation of the real timedata A is switched to the reproduction operation of the real time dataB. As a result, the real time data B is read from a part of thereproduction area 17 by the reproduction operation R1 after the accessoperation A2. The reason why the reproduction is performed from themiddle of the reproduction area is that the order of reproduction hasbeen changed by editing.

The real time data B may be reproduced from the start of thereproduction area 17. In this case, the size of the reproduction area 17is Y or greater. Therefore, the reproduction operation is switched tothe recording operation without the access operation A3 to thereproduction area 16.

The data reproduction means 506 instructs the optical disc drive 531 toreproduce the real time data B from the optical disc and transfers thereal time data B to be reproduced to the optical disc drive reproductionbuffer memory 511 (step S606).

The recording and reproduction switching means 502 determines whetherthe reproduction buffer memory 511 is full or not. When the reproductionbuffer memory 511 is determined to be full, the recording andreproduction switching means 502 switches the reproduction operation ofthe real time data B to the recording operation of the real time data A.When the reproduction buffer memory 511 is determined not to be full,the recording and reproduction switching means 502 continues thereproduction operation of the real time data B (step S607).

In FIG. 3, the reproduction buffer memory 511 becomes full in thereproduction operation R2. Thus, the reproduction operation of the realtime data B is switched to the recording operation of the real time dataA. As a result, the real time data A is recorded in the remaining areaof the recording area 14 in the recording operation W3 after the accessoperation A4.

When recording of all the data is completed, the file structureprocessing means 504 records a file entry in the file structure area 12in order to manage the areas in which real time data is recorded as realtime extents (step S608).

In this manner, the recording operation of the real time data A and thereproduction operation of the real time data B are switched to eachother while the data accumulation states in the recording buffer memoryand the reproduction buffer memory are checked.

For simultaneous recording and reproduction of n number of real timedata, a simultaneous recording and reproduction model including thefollowing is used: a pickup P for accessing an area in the informationrecording medium, an encoding module EMi for encoding real time data Di,a recording buffer WBi for accumulating the encoded real time data Di, areproduction buffer RBj for accumulating real time data Dj which is readfrom the information recording medium, and a decoding module DMj fordecoding real time data Dj accumulated in the reproduction buffer RBj.(This simultaneous recording and reproduction model will be referred toas an “n-simultaneous recording and reproduction model”, hereinafter.)In this case, the following operation is performed in each of theabove-mentioned steps.

Step S602: The unassigned area search means 503 searches for anunassigned area in the volume space in the information recording medium,and assigns at least one unassigned area in the volume space as an areaAi in which real time data Di is to be recorded.

Step S603: In compliance with the instruction from the data recordingmeans 505 for recording, the optical disc drive 531 executes a recordingoperation Wi for recording the real time data Di accumulated in therecording buffer WBi in the area Ai.

Step S605: While the recording operation Wi is being executed, therecording and reproduction switching means 502 determines whether therecording buffer WBi is empty or not. When the recording buffer WBi isdetermined to be empty, the recording and reproduction switching means502 switches the recording operation Wi to another recording operationWi or a reproduction operation Rj. When the recording buffer WBi isdetermined not to be empty, the recording and reproduction switchingmeans 502 continues the recording operation Wi.

Step S606: In compliance with the instruction from the data reproductionmeans 506 for reproduction, the optical disc drive 531 executes thereproduction operation Rj for reading the real time data Dj from thearea Aj in which the real time data Dj is recorded.

Step S607: While the reproduction operation Rj is being executed, therecording and reproduction switching means 502 determines whether thereproduction buffer RBj is full or not. When the reproduction buffer RBjis determined to be full, the recording and reproduction switching means502 switches the reproduction operation Rj to another reproductionoperation Rj or a recording operation Wi. When the reproduction bufferRBj is determined not to be full, the recording and reproductionswitching means 502 continues the reproduction operation Rj.

With reference to FIG. 6, a method for simultaneous recording andreproduction of two pieces of real time data is described. Thus, therecording operation and the reproduction operation are alternatelyswitched. For simultaneous recording and reproduction of n number ofreal time data, n may be an odd number, and the number of pieces of realtime data to be recorded may be different from the number of pieces ofreal time data to be reproduced. Therefore, a recording operation may beswitched to another recording operation, and a reproduction operationmay be switched to another reproduction operation.

Each of at least one area assigned as the area Ai is structured so as tofulfill the condition that the recording buffer WBi can be made empty byat most one access operation and at most two recording operations. Eachof at least one area assigned as the area Aj is structured so as tofulfill the condition that the reproduction buffer RBj can be made fullby at most one access operation and at most two reproduction operations.Fulfilling these two conditions is to fulfill the simultaneous recordingand reproduction condition.

The simultaneous recording and reproduction condition can be fulfilledwhere, for example, each of at least one area assigned as the area Aihas a size of Y or greater and each of at least one area assigned as thearea Aj has a size of Y or greater. The method for obtaining the minimumsize Y for each of the recording area and the reproduction area is asdescribed with reference to FIG. 1.Y=2×n×Ta×Vd×Vt÷(Vt−n×Vd)

In the above, Ta represents the access time required for the pickup P tomove between an innermost area and an outermost area of the informationrecording medium.

Vt represents the data transfer rate between the pickup P and therecording buffer WBi, and the data transfer rate between the pickup Pand the reproduction buffer RBj.

Vd represents the data transfer rate between the encoding module EMi andthe recording buffer WBi, and the data transfer rate between thedecoding module DMj and the reproduction buffer RBj, for all values of iand all values of j.

Here, i is any integer of 1 or greater and m or less, and j is anyinteger of (m+1) or greater and n or less. m is any integer whichfulfills m<n and is 1 or greater, and n is any integer of 2 or greaterwhich represents the number of a plurality of pieces of real time datato be simultaneously recorded and reproduced.

Skip recording may be performed to pre-assigned areas. “Skip recording”refers to a technique of performing recording while avoidingpre-detected defects or defects detected during data recording. Withreference to FIG. 8 which illustrates skip recording, it is assumedthat, for example, no defective sector is detected in an area 40 beforerecording and defective areas 42, 44 and 46 are detected duringrecording. In this case, data which was to be recorded in the defectivearea is recorded in the area next to the defective area in order toavoid the data from being recorded in the defective area. In the exampleof skip recording shown in FIG. 8, the recording operations areperformed in the order of SW1, SW2, SW3 and SW4. Since the access timeis short in skip recording, skip recording may be performed such thatareas including defects are avoided in units of ECC block, not in unitsof sector. Where the size of each ECC block is E, the access time toeach ECC block in such skip recording is E÷Vt. In order to guaranteecompatibility among apparatuses in simultaneous recording andreproduction, the number of ECC blocks to be skipped may be limited. Forexample, the ratio of the skippable area in skip recording to therecording area is defined as “e”. When skip recording is performed underthe simultaneous recording and reproduction condition described abovewith reference to FIG. 1, recording or reproduction is performed in anarea of Ye×(1−e) (Ye is the minimum size of the recording area), and thearea of Ye×e is skipped and only accessed to and is not recorded to. Thecondition for simultaneous recording and reproduction obtained inconsideration of skip recording with a limited ratio of skippable areais as follows.Ye×(1−e)÷Vt×(Vt−Vd)−Ta ×Vd −Ye ×e ÷Vt ×Vd=(3×Ta+Ye×(1−e)÷Vt)×Vd+Ye ×e÷Vt ×VdThus,Ye=4×Ta×Vd×Vt÷(Vt−e×Vt−2×Vd).

A buffer size Be required in this case is as follows.Be=(4×Ta+Ye×(1−e)÷Vt)×Vd+2×Ye×e÷Vt×Vd

The recording may be performed in units of ECC block, not in units ofsector.

Although not shown, a threshold in a buffer is predetermined such thatthe buffer is determined to be empty when the data amount in the bufferis below the threshold. A threshold in a buffer is predetermined suchthat the buffer is determined to be full when the data amount in thebuffer is above the threshold. Therefore, the size of the buffer memorymay contain a margin corresponding to the minimum reading or writingunit or a margin corresponding to the time period until the rotationrate becomes a desired value.

A recording operation and a reproduction operation are switched at anoptimal timing. Therefore, even when an error occurs during recording orreproduction, and as a result, recording and reproduction cannot beperformed for a certain time period, the return to the normal state israpidly realized.

FIG. 2 shows a model; neither the encoder nor the decoder are absolutelynecessary. A system handling only digital signals, such as a streamer,does not include an encoder or decoder. The present invention, whenapplied to a streamer, provides the effect of transferring audiovisualdata with no interruption.

EXAMPLE 2

In a second example of the present invention, a case where the transferrates of a plurality of pieces of real time data are different will bedescribed. In the first example, the simultaneous recording andreproduction condition is described in the case where the plurality ofpieces of real time data have the same transfer rate. In the secondexample, a simultaneous recording and reproduction condition is set foreach of the data having a high transfer rate and data having a lowtransfer rate. This allows data having a low transfer rate to berecorded even in a small continuous empty area, and also reduces therequired size of buffer memories.

FIG. 9 shows recording operations, reproduction operations and accessoperations for reproducing the real time data A having a high transferrate and recording the real time data B having a low transfer rate. Thesimultaneous recording and reproduction model is identical with thatshown in FIG. 2 which is described in the first example. The transitionin the data amounts in the recording buffer and the reproduction bufferduring the simultaneous recording and reproduction is described in thefirst example and will be omitted here.

FIG. 10 shows a layout of recording areas and reproduction areas in thedisc. The left side represents the inner side of the disc, and the rightside represents the outer side of the disc. In FIG. 10, reproductionareas 111, 112 and 113 are assigned as areas having the real time data Arecorded therein, and recording areas 114, 115 and 116 are assigned asareas in which the real time data B is to be recorded. The real timedata A is actually reproduced from an area 101 of the reproduction area111, areas 102 and 103 of the reproduction area 112, and an area 104 ofthe reproduction area 113. The real time data B is actually recorded inan area 105 of the recording area 114, areas 106 and 107 of therecording area 115, and an area 108 of the recording area 116.

In FIG. 9, A21 through A27 refer to operations of the pickup 74 ofmoving between areas to be accessed (access operations). It is assumedhere that the time required for each of the access operations A21through A27 is a time period required for the pickup 74 to move betweenan innermost area and an outermost area of the information recordingmedium (i.e., the maximum access time Ta). It is also assumed that thedata transfer rate between the pickup 74 and the recording buffer 72 andthe data transfer rate between the pickup 74 and the reproduction buffer73 are a constant rate Vt. It is also assumed that the data transferrate between the encoder 70 and the recording buffer 72 is Vd2, which isthe maximum value of a range in which the rate is variable. It is alsoassumed that the data transfer rate between the decoder 71 and thereproduction buffer 73 is Vd1, which is the maximum value of a range inwhich the rate is variable.

In a reproduction operation R21, the real time data A is read from thearea 101. After an access operation A21, in a reproduction operationR22, the real time data A is read from the area 102. Then, thereproduction operation of the real time data A is switched to therecording operation of the real time data B (access operation A22).

In a recording operation W21, the real time data B is recorded in thearea 105. After an access operation A23, in a recording operation W22,the real time data B is recorded in the area 106. Then, the recordingoperation of the real time data B is switched to the reproductionoperation of the real time data A (access operation A24).

Thus, the method of simultaneous recording and reproduction according tothe present invention is designed so as to fulfill the simultaneousrecording and reproduction condition that a recording operation isswitched to a reproduction operation by at most one access operation andat most two recording operations and also a reproduction operation isswitched to a recording operation by at most one access operation and atmost two reproduction operations.

In the reproduction operation of the real time data A, data accumulatedin the reproduction buffer 73 is accumulated at Vt−Vd1. In the accessoperation and the recording operation of the real time data B, data inthe reproduction buffer 73 is consumed at Vd1. The data amount which isaccumulated in the reproduction buffer 73 during the reproductionoperation R21, the access operation A21 and the reproduction operationR22 is equal to the data amount consumed from the reproduction buffer 73during the access operation A22, the recording operation W21, the accessoperation A23, the recording operation W22 and the access operation A24.Accordingly, the following expressions are satisfied, where Y1 is theminimum size of at least one reproduction area assigned as an areahaving the real time data A recorded therein, and Y2 is the minimum sizeof at least one recording area assigned as an area in which the realtime data B is to be recorded.Y1÷Vt×(Vt−Vd1)=(4Ta+Y2÷Vt)×Vd1Y2÷Vt×(Vt−Vd2)=(4Ta+Y1÷Vt)×Vd2

By manipulating these expressions, the following expressions forobtaining the minimum size Y1 for the reproduction area and the minimumsize Y2 for the recording area are obtained.Y1=(4Ta×Vt×Vd1)÷(Vt−Vd1−Vd2)Y2=(4Ta×Vt×Vd2)÷(Vt−Vd1−Vd2)

The simultaneous recording and reproduction condition for recording andreproducing two pieces of real time data having different transfer rateswithout missing any part of the data can be fulfilled where each of atleast one reproduction area assigned as an area having the real timedata A recorded therein has a size of Y1 or greater, and each of atleast one recording area assigned as an area in which the real time dataB is to be recorded has a size of Y2 or greater.

A buffer size B1 required for the reproduction buffer 73 and a buffersize B2 required for the recording buffer 72 are obtained by thefollowing expressions.B1=(4Ta+Y2÷Vt)Vd1B2=(4Ta+Y1÷Vt)Vd2

By setting Vd1>Vd2 as above, Y2 and B2 can be smaller than Y1 and B1,respectively.

In the case where the maximum transfer rate of the data to be recordedand reproduced is known before the real time data A is recorded so as torealize simultaneous recording and reproduction of real time data, datarecording is made possible by assigning a large continuous empty area,which is larger than the size fulfilling the simultaneous recording andreproduction condition, as a recording area.

The simultaneous recording and reproduction of the second example can beperformed by the recording and reproduction method described in thefirst example with reference to FIG. 6 by using, for searching for anunassigned area, different expressions from those of the first examplefor obtaining the simultaneous recording and reproduction condition.

In the case where the transfer rate is not known until immediatelybefore the recording is performed, the real time data A, which is to berecorded first, is set to be recorded at the maximum transfer rate inthe range. The real time data B, which is to be recorded while the realtime data A is being reproduced, is set to be recorded at the maximumtransfer rate permitted by the system. Thus, an area which fulfills thesimultaneous recording and reproduction condition can be retrieved as anarea in which the real time data A is to be recorded. When recording thereal time data B, the transfer rate thereof is already known. Thus, anappropriate size of recording area can be retrieved.

The information recording and reproduction apparatus in the secondexample has the same structure as that of the first example except forthe sizes of the recording buffer memory and the reproduction buffermemory. The algorithm for switching the recording operation and thereproduction operation is the same as that of the first example. Namely,when the recording buffer memory becomes empty, the recording operationis switched to the reproduction operation. When the reproduction buffermemory becomes full, the reproduction operation is switched to therecording operation.

The present invention is applicable to additional recording of audiodata to AV data compressed by MPEG. The minimum size of the reproductionarea for the MPEG data can be obtained by presetting the transfer rateof the audio data to be after-recorded. After-recording of the audiodata can be performed by recording the audio data at an appropriatetiming while reproducing the MPEG data which is already recorded.

As described below, it is also possible to after-record two channels ofaudio data by defining the simultaneous recording and reproductioncondition for a larger number of pieces of real time data. For example,it is possible to first record MPEG data and then record the backgroundmusic and the narration separately.

FIG. 11 shows recording operations, reproduction operations and accessoperations for three pieces of real time data having different transferrates. Like in FIG. 9, R31 through R38 refer to reproduction operations,W31 through W34 refer to recording operations, and A31 through A41 referto access operations. Reference numerals 121 through 128 each representa part of a reproduction area from which the real time data is actuallyto be read, and reference numerals 129 through 132 each represent a partof a recording area in which the real time data is actually to berecorded. Based on FIG. 11, the simultaneous recording and reproductioncondition for the three pieces of real time data can be obtained asfollows in a similar manner as for the two pieces of real time data.Y1=(6Ta×Vt×Vd1)÷(Vt−Vd1−Vd2−Vd3)Y2=(6Ta×Vt×Vd2)÷(Vt−Vd1−Vd2−Vd3)Y3=(6Ta×Vt×Vd3)÷(Vt−Vd1−Vd2−Vd3)B1=(6Ta+Y2÷Vt+Y3÷Vt)Vd1B2=(6Ta+Y3÷Vt+Y1÷Vt)Vd2B3=(6Ta+Y1÷Vt+Y2÷Vt)Vd3

In the above expressions, Y is the minimum size of the reproduction areaor the recording area, Vd is the transfer rate of the data to bereproduced or recorded, and B is the size of the reproduction buffer orthe recording buffer. The numerals added to Y, Vd and B each representthe number assigned to the real time data to be reproduced or recorded.

For simultaneous recording and reproduction of n number of real timedata, the “n-simultaneous recording and reproduction model” describedabove is used. A minimum size Yi for each of at least one recording areaassigned as an area Ai in which real time data Di is to be recorded, asize Bi of a recording buffer WBi for accumulating the real time dataDi, a minimum size Yj for each of at least one reproduction areaassigned as an area Aj having real time data Dj recorded therein, and asize Bj of a reproduction buffer RBj for accumulating the real time dataDj are obtained by the following expressions.Yi=(2×n×Ta×Vt×Vdi)÷{Vt−(Vd1+Vd2+ . . . +Vdn)}Yj=(2×n×Ta×Vt×Vdj)÷{Vt−(Vd1+Vd2+ . . . +Vdn)}Bi={2×n×Ta+(Y1+Y2+ . . . +Yn)÷Vt−Yi÷Vt)VdiBj={2×n×Ta+(Y1+Y2+ . . . +Yn)÷Vt−Yj÷Vt)Vdj

Ta is the access time required for the pickup P to access between aninnermost area and an outermost area of the information recordingmedium.

Vt is the data transfer rate between the pickup P and the recordingbuffer WBi, and also the data transfer rate between the pickup P and thereproduction buffer RBj.

Vdi is the data transfer rate between the encoding module EMi and therecording buffer WBi.

Vdj is the data transfer rate between the decoding module DMj and thereproduction buffer RBj.

In addition, i is any integer of 1 or greater and m or less, and j isany integer of (m+1) or greater and n or less. m is any integer whichfulfills m<n and is 1 or greater. n is any integer of 2 or greater whichrepresents the number of the plurality of pieces of real time data forsimultaneous recording and reproduction.

The above-described simultaneous recording and reproduction condition isapplicable to the case where the transfer rate of the plurality ofpieces of real time data is the same (i.e., in the case where Vd1=Vd2= .. . =Vdn).

EXAMPLE 3

In a third example, a case where a plurality of pieces of real time datato be reproduced and recorded have different and fixed transfer rateswill be described. DV-format data which is used for digital videocameras has a fixed transfer rate, not a variable transfer rate as inthe MPEG format. With the real time data having a fixed transfer rate,the reproduction operation and the recording operation can be switchedto each other in units of recording area or reproduction area once anoptimal size for each of the recording area and the reproduction area isdetermined. This simplifies the switching operation and also reduces thesize of each of the recording area and the reproduction area.

FIG. 28 shows a layout of recording areas for simultaneous recording andreproduction of two pieces of real time data. As shown here, each of therecording areas has a different and fixed size in accordance with thetype of data to be recorded in the area.

FIG. 12 shows recording operations, reproduction operations and accessoperations for two pieces of real time data having different transferrates. Like in FIG. 9, R51 and R52 refer to reproduction operations, W51and W52 refer to recording operations, and A51 through A53 refer toaccess operations. Reference numerals 151 and 152 each represent areproduction area, and reference numerals 153 and 154 each represent arecording area. Since the transfer rates of the plurality of pieces ofreal time data are fixed, the reproduction operation and the recordingoperation are switched to each other in units of area. Accordingly, whenreproduction from one reproduction area is completed, the reproductionoperation can be switched to the recording operation. When recording inone recording area is completed, the recording operation can be switchedto the reproduction operation.

The information recording and reproduction apparatus in the thirdexample has the same structure as that of the information recording andreproduction apparatus shown in FIG. 5 except for the operations of theunassigned area search means 503 and the recording and reproductionswitching means 502.

FIG. 27 shows a procedure of a method for simultaneous recording andreproduction. Such a method is stored, for example, in the form of aprogram in a memory in the system control section 501. Such a programcan be executed by, for example, the microcomputer in the system controlsection 501.

The procedure shown in FIG. 27 is the same as that of the first example(FIG. 6) except for the expressions for obtaining the simultaneousrecording and reproduction condition used in the step for searching foran unassigned area (S701) and the condition for switching the recordingoperation and the reproduction operation to each other (S702, S703).

In step S701, the unassigned area search means 503 searches for anunassigned area having a size of Y1 (or Y2) and assigns at least oneunassigned area thus found as an area in which the real time data B isto be recorded. A method for obtaining the size Y1 (or Y2) of therecording area will be described below.

In step S702, in the recording operation of the real time data B, therecording and reproduction switching means 502 determines whether or notthe real time data B has been recorded up to the end of the at least onerecording area assigned as an area in which the real time data B is tobe recorded. When it is determined that the real time data B has beenrecorded up to the end of the recording area, the recording operation ofthe real time data B is switched to the reproduction operation of thereal time data A. When it is determined that the real time data B hasnot been recorded up to the end of the recording area, the recordingoperation of the real time data B is continued.

In step S703, in the reproduction operation of the real time data A, therecording and reproduction switching means 502 determines whether or notthe real time data A has been reproduced up to the end of at least onereproduction area assigned as a reproduction area having the real timedata A recorded therein. When it is determined that the real time data Ahas been reproduced up to the end of the reproduction area, thereproduction operation of the real time data A is switched to therecording operation of the real time data B. When it is determined thatthe real time data A has not been reproduced up to the end of thereproduction area, the reproduction operation of the real time data A iscontinued.

The data amount which is accumulated in the reproduction buffer 73during the reproduction operation R51 is equal to the data amountconsumed from the reproduction buffer 73 during the access operationA51, the recording operation W51 and the access operation A52.Accordingly, the following expressions are satisfied, where Y1 is thesize of at least one reproduction area assigned as an area having thereal time data A recorded therein, and Y2 is the size of at least onerecording area assigned as an area in which the real time data B is tobe recorded.Y1÷Vt×(Vt−Vd1)=(2Ta+Y2÷Vt)×Vd1Y2÷Vt×(Vt−Vd2)=(2Ta+Y1÷Vt)×Vd2

By manipulating these expressions, the following expressions forobtaining the size Y1 for the reproduction area and the size Y2 for therecording area are obtained.Y1=(2Ta×Vt×Vd1)÷(Vt−Vd1−Vd2)Y2=(2Ta×Vt×Vd2)÷(Vt−Vd1−Vd2)

A buffer size B1 required for the reproduction buffer 73 and a buffersize B2 required for the recording buffer 72 are obtained by thefollowing expressions.B1=(2Ta+Y2÷Vt)Vd1B2=(2Ta+Y1÷Vt)Vd2

By setting the simultaneous recording and reproduction condition for theplurality of pieces of real time data each having a fixed transfer rateutilizing the different recording rates thereof as described above, itis made possible to record data having a low transfer rate in a smallerrecording area. Thus, empty areas in the disc can be effectively used.

FIG. 13 shows recording operations, reproduction operations and accessoperations for three pieces of real time data considered in a similarmanner. The simultaneous recording and reproduction condition for thethree pieces of real time data can be obtained as follows.Y1=(3Ta×Vt×Vd1)÷(Vt−Vd1−Vd2−Vd3)Y2=(3Ta×Vt×Vd2)÷(Vt−Vd1−Vd2−Vd3)Y3=(3Ta×Vt×Vd3)÷(Vt−Vd1−Vd2−Vd3)B1=(3Ta+Y2÷Vt+Y3÷Vt)Vd1B2=(3Ta+Y3÷Vt+Y1÷Vt)Vd1B3=(3Ta+Y1÷Vt+Y2÷Vt)Vd1

For simultaneous recording and reproduction of n number of real timedata, the “n-simultaneous recording and reproduction model” describedabove is used. Referring to FIG. 27, the following operations areperformed in steps S701, S603, S606, S702, and S703.

Step S701: The unassigned area search means 503 searches for anunassigned area in the volume space in the information recording mediumand assigns at least one unassigned area in the volume space as an areaAi in which real time data Di is to be recorded.

Step S603: In compliance with the instruction for recording from thedata recording means 505, the optical disc drive 531 executes arecording operation Wi for recording the real time data Di accumulatedin a recording buffer WBi in the area Ai.

Step S702: In the recording operation Wi, the recording and reproductionswitching means 502 determines whether or not the real time data Di hasbeen recorded up to the end of the at least one recording area assignedas the area Ai. When it is determined that the real time data Di hasbeen recorded up to the end of the recording area, the recording andreproduction switching means 502 switches the recording operation Wi toanother recording operation Wi or a reproduction operation Rj. When itis determined that the real time data Di has not been recorded up to theend of the recording area, the recording and reproduction switchingmeans 502 continues the recording operation Wi.

Step S606: In compliance with the instruction for reproduction from thedata reproduction means 506, the optical disc drive 531 executes areproduction operation Rj for reproducing real time data Dj from thearea Aj having the real time data Dj recorded therein.

Step S703: In the reproduction operation Rj, the recording andreproduction switching means 502 determines whether or not the real timedata Dj has been reproduced up to the end of at least one reproductionarea assigned as the area Aj. When it is determined that the real timedata Dj has been reproduced up to the end of the reproduction area, therecording and reproduction switching means 502 switches the reproductionoperation Rj to another reproduction operation Rj or a recordingoperation Wi. When it is determined that the real time data Dj has notbeen reproduced up to the end of the reproduction area, the recordingand reproduction switching means 502 continues the reproductionoperation Rj.

With reference to FIG. 27, a method for simultaneous recording andreproduction of two pieces of real time data is described. Thus, therecording operation and the reproduction operation are alternatelyswitched. For simultaneous recording and reproduction of n number ofreal time data, n may be an odd number, and the number of pieces of realtime data to be recorded may be different from the number of pieces ofreal time data to be reproduced. Therefore, a recording operation may beswitched to another recording operation, and a reproduction operationmay be switched to another reproduction operation.

Each of at least one area assigned as the area Ai is structured so as tofulfill the condition that the real time data Di, which is accumulatedin the recording buffer WBi during n number of access operationsaccompanying the recording/reproduction operation switching, (m−1)number of recording operations and (n−m) number of reproductionoperations, can be recorded by one recording operation.

Each of at least one area assigned as the area Aj is structured so as tofulfill the condition that the real time data Dj, which is accumulatedin the reproduction buffer RBj during one reproduction operation, can beconsumed during n number of access operations accompanying therecording/reproduction operation switching, (n−m−1) number ofreproduction operations and m number of recording operations. Fulfillingthese two conditions is to fulfill the simultaneous recording andreproduction condition.

The simultaneous recording and reproduction condition can be fulfilledwhere, for example, each of at least one area assigned as the area Ai inwhich the real time data Di is to be recorded has a size of Yi and eachof at least one area assigned as the area Aj from which the real timedata Dj is to be reproduced has a size of Yj.

The size Yi for a recording area, the size Yj for a reproduction area,the size Bi for the recording buffer WBi, and the size Bj for thereproduction buffer RBj are obtained by the following expressions.Yi=(n×Ta×Vt×Vdi)÷{Vt−(Vd1+Vd2+ . . . +Vdn)}Yj=(n×Ta×Vt×Vdj)÷{Vt−(Vd1+Vd2+ . . . +Vdn)}Bi={n×Ta+(Y1+Y2+ . . . +Yn)÷Vt−Yi÷Vt}VdiBj={n×Ta+(Y1+Y2+ . . . +Yn)÷Vt−Yj÷Vt}Vdj

Ta is the access time required for the pickup P to access between aninnermost area and an outermost area of the information recordingmedium.

Vt is the data transfer rate between the pickup P and the recordingbuffer WBi, and also the data transfer rate between the pickup P and thereproduction buffer RBj.

Vdi is the data transfer rate between the encoding module EMi and therecording buffer WBi.

Vdj is the data transfer rate between the decoding module DMj and thereproduction buffer RBj.

In addition, i is any integer of 1 or greater and m or less, and j isany integer of (m+1) or greater and n or less. m is any integer whichfulfills m<n and is 1 or greater. n is any integer of 2 or greater whichrepresents the number of the plurality of pieces of real time data forsimultaneous recording and reproduction.

Next, access performance of a drive for performing recording to andreproduction from a disc will be described. FIG. 14 shows the details ofthe access time of the drive for accessing a sector of a target track.When the distance for access is longer, the access time is longer by thedistance corresponding to the movement (rough seek) of the pickup. Forrecording data on a CLV system (constant linear velocity system) disc,the rotation rate of the disc needs to be changed in accordance with theradial position to be accessed. Therefore, a spindle lock time isrequired for accelerating or decelerating the rotation of a spindlemotor to match a prescribed rotation rate. The spindle motor is providedfor rotating the disc. Once the rotation rate of the disc is locked, thesearch for an address becomes possible. Then, the movement of the pickupfor performing multiple jumps in units of a plurality of tracks toaccess the target track (fine seek) requires some time. The multiplejumps are performed mainly using an optical system. After this, thepickup waits for the prescribed sector to come to the positioncorresponding to the pickup. Thus, recording or reproduction is madepossible. When the distance for access is within a range of fine seek,the access time is the sum of the fine seek time and the time period ofrotational latency. When the distance for access is ⅓ of the disccapacity, the access time is the sum of the corresponding spindle locktime and the rough seek time.

By pre-checking the access performance of the drive, the time for accessbetween extents for simultaneous recording and reproduction can be theaccess time obtained by the access performance of the drive, not thefull seek time. Since such an access time is shorter than the full seektime, data can be recorded in a smaller continuous empty area. Even whenthe extent is made shorter by editing, it is more often determined thatcontinuous reproduction is possible.

FIG. 26 shows access operations and a layout of recording areas forsimultaneous recording and reproduction of three pieces of real timedata. In the case where, for example, the recording areas 128 and 129are distanced from each other as far as an innermost area and anoutermost area of the disc are distanced, the time required for each ofaccess operations A40, A34 and A36 substantially equals the full seektime. In the case where the recording areas 122 and 121 are distancedfrom each other by approximately 100 tracks, the time required for theaccess operation A31 substantially equals the fine seek time.

In the method for simultaneous recording and reproduction shown in FIG.6, the access time (first access time or second access time) isestimated in step S602 in which an unassigned area is searched for. Inthe method for simultaneous recording and reproduction shown in FIG. 27,the access time is estimated in step S701 in which an unassigned area issearched for. Such an estimation of the access time is performed by theunassigned area search means 503 (FIG. 5).

In consideration of the estimated access time, the simultaneousrecording and reproduction condition described in the second example isas follows.Yi={2×(T1+ . . . +Tn)×Vt×Vdi}÷{Vt−(Vd1+Vd2+ . . . +Vdn)}Yj={2×(T1+ . . . +Tn)×Vt×Vdj}÷{Vt−(Vd1+Vd2+ . . . +Vdn)}Bi={2×(T1+ . . . +Tn)+(Y1+Y2+ . . . +Yn)÷Vt−Yi÷Vt}VdiBj={2×(T1+ . . . +Tn)+(Y1+Y2+ . . . +Yn)÷Vt−Yj÷Vt}Vdj

Tk is a first access time or a second access time. The first access timeis the access time required for the pickup P to access from an area Akto an area Al. The second access time is the access time required toaccess from one area among at least one area assigned as the area Ak toanother area. k and 1 are each any integer of 1 or greater and n orless. k≠1.

In addition, i is any integer of 1 or greater and m or less, and j isany integer of (m+1) or greater and n or less. m is any integer whichfulfills m<n and is 1 or greater, and n is any integer of 2 or greaterwhich represents the number of a plurality of pieces of real time data.

The above-described simultaneous recording and reproduction condition isapplicable to the case where the transfer rate of the plurality ofpieces of real time data is the same (i.e., in the case where Vd1=Vd2= .. . =Vdn).

In consideration of the estimated access time, the simultaneousrecording and reproduction condition described in the third example isas follows.Yi={(T1+ . . . +Tn)×Vt×Vdi}÷{Vt−(Vd1+Vd2+ . . . +Vdn)}Yj={(T1+ . . . +Tn)×Vt×Vdj}÷{Vt−(Vd1+Vd2+ . . . +Vdn)}Bi={(T1+ . . . +Tn)+(Y1+Y2+ . . . +Yn)÷Vt−Yi Vt}VdiBj={(T1+ . . . +Tn)+(Y1+Y2+ . . . +Yn)÷Vt−Yj Vt}Vdi

Tk is the access time required for the pickup P to access from an areaAk to an area Al. k and 1 are each any integer of 1 or greater and n orless. k≠1.

In addition, i is any integer of 1 or greater and m or less, and j isany integer of (m+1) or greater and n or less. m is any integer whichfulfills m<n and is 1 or greater, and n is any integer of 2 or greaterwhich represents the number of a plurality of pieces of real time datato be simultaneously recorded and reproduced.

The above-described simultaneous recording and reproduction condition isapplicable to the case where the transfer rate of the plurality ofpieces of real time data is the same (i.e., in the case where Vd1=Vd2= .. . =Vdn).

Next, a method for improving the utilization efficiency and editingefficiency of the disc by restricting the full seek time will bedescribed. FIG. 15 shows the relationship between the rotation ratedifference of the spindle motor of the drive and the access time. Withthe premise of TRQ=(N1−N2)·J/(dt·Kj), the access time Tacc is obtainedas follows.Tacc=(spindle lock time)+(time period of rotational latency)+constant=(N1−N2)×J÷(TRQ×KJ)+Trev+constant ∓A×dN+B

In the above expression, A and B are each a constant, dN is the rotationrate difference (=N1−N2), dt is the spindle lock time, J is the inertialof the disc, Kj is the conversion constant, N1 is the rotation ratebefore access, N2 is the rotation rate after access, Trev is the timeperiod of rotational latency, and TRQ is the torque of the motor. Theabove-mentioned access performance model is set based on therelationship between the rotation rate difference of the disc and theaccess time. As described above with reference to FIG. 14, for movingthe pickup to a position close to the target track, rough seek and achange in the rotation rate of the spindle motor are necessary. With theperformance of the spindle motor used in an optical disc drive, theaccess time is dominantly influenced by the change in the rotation rateof the spindle motor. Paying attention to the fact that the spindle locktime is in proportion to the rotation rate difference, the access timecan be represented by the above expression. The time period ofrotational latency (Trev), when being sufficiently smaller than thespindle lock time, can be omitted. In that case, the access time Tacccan be linearly estimated with respect to the rotation rate differencedN of the disc.

Once the initial position and the target position of the pickup arefound, the rotation rate and the rotation rate difference of the disccan be uniquely obtained from the relationship thereof with the linearvelocity of the disc. Where A1 is the address before access, A2 is theaddress after access, r1 is the radial position of A1, r2 is the radialposition of A2, and r0 is the radial position of address 0, theaddresses A1 and A2 are obtained as follows. The value of an address isin proportion to the area of a circle having the address on the outercircumference thereof. C is a constant.A1=C·(π·r1−r1−π·r0·r0)A2=C·(π·r2−r2−π·r0·r0)

The rotation rate at a certain address is in inverse proportion to theradial position thereof. Therefore, where N1 is the rotation rate of A1,N2 is the rotation rate of A2, and D is the constant,N1=D/r1, andN2=D/r2.

Using the above expressions, the rotation rate can be obtained from theaddress.

FIG. 16 shows the relationship between the radial position and therotation rate of a disc having a diameter of 12 cm, a capacity of 25 GB,and a reading rate of 72 Mbps. The logical product of the radialposition and the rotation rate is constant. Therefore, when an access ofa given distance is made in a radial direction, the access time isshorter at an outer portion of the disc than at an inner portion of thedisc since the rotation rate difference is smaller at the outer portionof the disc than the inner portion. The volume space extends between aposition having a radius of 24 mm and a position having a radius of 58mm, and the full seek time is in proportion to the rotation ratedifference of 2270 rpm. It is assumed now that AV data is to be recordedin an area extending between a position having a radius of 38 mm and aposition having a radius of 58 mm. The access time, which is inproportion to the rotation rate difference of 840 rpm, is about 1/2.7 of2270 rpm. In FIG. 29, the longest access time from a position having aradius of 24 mm to a position having a radius of 58 mm is 1000 msec. Insuch a case, the longest access time is reduced to 370 msec. byproviding a recording area between a position having a radius of 38 mmand a position having a radius of 58 mm. The capacity of the areabetween the position having a radius of 38 mm and the position having aradius of 58 mm is 17 GB, which is about 30 percent less than the casewhere the longest access time is 1000 msec. Unless a significantly largecapacity is required, an outer portion of the disc can be set as ahigh-speed access zone in which AV data is to be recorded. In thismanner, the access time can be significantly reduced, and the sizerequired for a continuous recording area under the simultaneousrecording and reproduction condition can be reduced in proportion to theaccess time. Owing to such a high-speed access zone, even when theextent is shortened, continuous simultaneous recording and reproductionis made possible more often. This is especially useful forafter-recording (post-recording), chasing reproduction or the like.

When recording is performed utilizing the above-describedcharacteristics of the disc, the discs may be classified into discshaving a high-speed access zone and discs with no such zone. Informationindicating to which class the disc belongs may be recorded in thelead-in area or the volume space. For example, the disc having ahigh-speed access zone is classified as class 1, and the disc having nosuch zone is classified as class 0. The maximum access time in thehigh-speed access zone may be recorded together with the information onthe class. Such settings improve inter-apparatus compatibility since anoptical disc apparatus on which the disc is mounted can find theinformation on the class of the disc.

When an optical disc having a capacity of 25 GB is used for a consumervideo recorder, which has the same functionality as, for example, a VTR,such an optical disc realizes a recording time as long as 10 hours. Thisallows various types of processing to be performed with one disc, suchas material editing, as well as timer recording. The editing performanceafter recording can be improved where a plurality of high-speed accesszones are set.

When a high-speed access zone is set in a one-layer disc, the capacityis small. This problem is solved in the case of a two-layer disc, whichhas a high-speed access zone formed of (i) a zone of a recording surfaceof the first layer and (ii) a zone of a recording surface of a secondlayer, the zones being at the same radial position. Precisely, the zonesof the two recording surfaces are not exactly at the same radialposition due to the physical production process. However, the accesstime required for accessing between a target track in the first layerand a target track in the second layer is about the same as the sum of afocus switching time required by the pickup and the time period ofrotational latency, and thus is generally shorter than the fine seektime. The time required for accessing between the target tracks in thelayers is sufficiently shorter than the access time from an innermostportion to an outermost portion of the high-speed access zone.

For simultaneous recording and reproduction of n number of real timedata, areas Ai in which real time data Di is to be recorded and areas Ajfrom which real time data Dj is to be reproduced may be provided in anouter portion of the information recording medium (for example, in thehigh-speed access zone) for all the values of i and j. Thus, the accesstime can be shortened.

EXAMPLE 4

In the first, second and third examples, the basics of the presentinvention for simultaneous recording and reproduction are described. Ina fourth example of the present invention, actual simultaneous recordingand reproduction will be described by way of three specific examples ofafter-recording (post-recording). In the fourth example, an area inwhich new audio data is to be recorded is determined while pre-recordedvideo data and audio data are being reproduced, and the new audio datais additionally recorded to the originally recorded audio data. In thecase where the audio data and the video data are not recorded as oneMPEG stream but are recorded in separate areas, the audio data and thevideo data can be regarded as being two pieces of real time data. Insuch a case, the simultaneous recording and reproduction is realized bythe methods described in the first, second and third examples.

FIGS. 17, 18 and 19 show a method for after-recording data on a disc inwhich audio data and video data encoded in a mixed manner are recorded,and a method for reproducing data from such a disc. After-recording ofthe audio data is assumed to be performed in a pre-determined recordingarea. In this example, the audio data and video data encoded in a mixedmanner such as, for example, MPEG data and DV data will be referred toas “AVM (Audio Video Mix Data)”. FIG. 17 shows an arrangement of the AVMdata and data for after-recording on a disc. A recording area for audiodata to be after-recorded is defined by a prescribed period (recordingareas 180, 182, 184, 186, 188 and 190). Recording areas 181, 183, 185,187, 189 and 191 have the AVM data recorded therein. The numerals addedto AVM (0 of AVM0 through p+3 of AVMp+3) each represent the numberassigned to the data in the order of address.

In the after-recording in this example, audio data is recorded whilereproducing the AVM data. Since the AVM data is reproduced after beingaccumulated in the buffer, the pickup needs to read the data from thedisc in advance. Therefore, audio data cannot be after-recorded in anarea immediately after a recording area of the AVM data. According tothe present invention, a recording area for after-recording is setbefore a recording area of the AVM data, such that the size of thereproduction buffer is as small as possible. Owing to such anarrangement, reproduction can be started immediately after the start ofthe reading of the video data, which is performed after the audio datais read. Thus, the size of the reproduction buffer can be reduced. Inthe case where the video data is read before the audio data, thereproduction can only be started after the start of the reading of theaudio data which is performed after the video data is read. A reason whythe audio data is read before the video data according to the presentinvention is that in this way, the time required for an image to beoutput is shorter. The AVM data has a higher transfer rate than that ofthe audio data to be after-recorded. Therefore, if the AVM data is readfirst, the image can only be output after the recording area forafter-recording is accessed. It is preferable to read the audio databefore the video data. In this case, once the after-recorded audio datarecorded in a small recording area is read and the recording area of theAVM data is accessed, the image can be output.

The reproduction start position is set in the recording area 181, thepositions to start the after-recording of audio data and thecorresponding video data are set respectively in the recording areas 182and 183, and the after-recording termination positions are set in therecording areas 188 and 189. The reproduction termination position isset in the recording area 191.

FIG. 18 shows the order of the recording areas shown in FIG. 17 to beaccessed for after-recording. It is difficult to after-record data at anappropriate timing after the AVM data is read, since the recording areafor after-recording is immediately before a recording area of the AVMdata. Therefore, data is after-recorded in correspondence with the AVMdata which is immediately previous to the AVM data which has just beenread. For example, after AVM2 is reproduced, data corresponding to AVM1is after-recorded in a recording area immediately before AVM1. In thismanner, after AVM data is read, audio data corresponding to differentAVM data which has already been read is after-recorded. Thus,simultaneous recording and reproduction can be realized.

P is the number of the sets of continuous areas, from each of whichwhole data is read completely (P≧0). Tpr1AV is the net time periodrequired for reading AVM0 from the reproduction start position. Thelabel “repeated P times” means that, for example, in the case of P=3,A2, AVM2, A3, AVM3, A4, and AVM4 exist in the range of P number ofcontinuous areas. As described above regarding skip recording, whenthere are “a” number of defective ECC blocks in the recording area ofAVM0, the time a×Ts is required in addition to Tpr1AV, where Ts is thetime for reading one ECC block. Tf1, Tf2, Tfi, and Tfj each represent anaccess time between recording areas, which is approximately within therange of fine seek. Tpr2AV is the time required for reading data in therecording area of AVM1 up to the after-recording start position. TinAVis the time required for reading data from the after-recording startposition until the end of the recording area of AVM1. ToutAV is the timerequired for reading data in a recording area of AVM until theafter-recording termination position. TcA is the net time periodrequired for reading after-recorded audio data. TcAV is the net timeperiod required for reading AVM data. TinA is the time period requiredfor reading after-recorded data from the after-recording start position.ToutA is the time required for reading after-recorded data until theafter-recording termination position. Tpo1AV is the time required forreading data in a recording area in which the after-recordingtermination position is set, from the after-recording terminationposition. Tpo2AV is the time required for reading data in a recordingarea in which the reproduction termination position is set, until thereproduction termination position. “a” represents the number of ECCblocks to be skipped in a recording area of the AVM, and “b” representsthe number of ECC blocks to be skipped in a recording area forafter-recording.

Hereinafter, a simultaneous recording and reproduction condition forrealizing after-recording of data in the order of the recording areas tobe accessed shown in FIG. 18 will be discussed. As long as the size ofthe real time data recorded on a disc is larger than the logical productof (i) the time required from the start of the reading of the data untilthe next recording area is accessed and (ii) the transfer rate of thedata, the reproduction buffer does not become empty. Thus, the followingexpressions are obtained.Y/Vd≧Tpr1AV+Tf1+TcAV+Tf2+TcAV+2*Tfj+TinA+(P−1)*(TcAV+TcA+2*Tfj)+TcAV+2*Tfj+TcA+Tpo2AV+(P+1)*(a+b)*Ts+3*a*TsY=(Tpr1AV+(P+2)*TcAV+Tpo2AV)*VtTinAV*Vt*(VdA/Vd)=TinA*VtToutAV*Vt*(VdA/Vd)=ToutA*VtTcAV*Vt*(VdA/Vd)=TcA*VtTcAV=Tpr2AV+TinAV=ToutAV+Tpo1AV

Y is the size of the AVM data in FIG. 17 recorded in a zone from thereproduction start position until the reproduction termination position.Vd is the transfer rate of the AVM data between the decoding module andthe reproduction buffer. VdA is the transfer rate of the audio data forafter-recording between the encoding module and the recording buffer. Vtis the transfer rate by which the pickup P reads the data from the disc.Accordingly, the following expression is obtained.Y/Vd≧(Tf1+Tf2+(P+1)*2*Tfj+(P+1)*(a+b)*Ts+3*a*Ts−(Tpr1AV+Tpr2AV+ToutAV+Tpo1AV+Tpo2AV)*VdA/Vd)*Vt/(Vt−Vd−VdA)

Regarding one cycle of after-recording in which the AVM data is read,the recording area for audio data for after-recording is accessed, theaudio data is after-recorded, and the next recording area of the AVMdata is accessed, the following expressions are obtained.Y′/Vd≧TcAV+2*Tfj+TcA+(a+b)*TsY′=TcAV*Vt

Y′ is the size of the recording area of the AVM, and is, for example,the size of the recording area 187 in FIG. 17. Accordingly, thefollowing expression is obtained.Y′/Vd≧(2*Tfj+(a+b)*Ts)*Vt/(Vt−Vd−VdA)

Regarding the section from the reproduction start position to Tf2, thefollowing expressions are obtained in consideration of the influence ofthe reproduction start position which is set in the middle of therecording area 181.Y″/Vd≧Tpr1AV+Tf1+TcAV+Tf2+2*a*TsY″=(Tpr1AV+TcAV)*Vt

Accordingly, the following expression is obtained.Y″/Vd≧(Tf1+Tf2+2*a*Ts)*Vt/(Vt−Vd)

When all the above expressions are satisfied, after-recording is madepossible.

It is understood that even if one of the expressions in which the leftside is Y′/Vd is not satisfied, simultaneous recording and reproductioncannot be performed in the range of P number of continuous areas. Inorder to check at which access operation simultaneous recording andreproduction is disabled, the above expressions are set for each ofprescribed sections.

FIG. 19 shows the order of the recording areas to be accessed forreproducing data after after-recording. Data can be read withoutrequiring any access time since the after-recorded data is before therecording area of the AVM data. The reproduction condition for audiodata and video data is as follows.YV/VdV≧Tpr1AV+Tf1+TinA+TcAV+P*(TcAV+TcA)+ToutA+Tf2+TcAV+Tf3+Tpo2AV+(P+2)*(a+b)*Ts+2*a*TsYV=(Tpr1AV+(P+2)*TcAV+Tpo2AV)*Vt*(VdV/Vd)YA/VdA≧Tpr1AV+Tf1+TinA+TcAV+P*(TcAV+TcA)+ToutA+Tf2+TcAV+Tf3Tpo2AV+(P+2)*(a+b)*Ts+2*a*TsYA=(Tpr1AV+Tpr2AV+Tpo1AV+Tpo2AV)*Vt*(VdA/Vd)+(TinA+P*TcA+ToutA)*VtTinAV*Vt*(VdA/Vd)=TinA*VtToutAV*Vt*(VdA/Vd)=ToutA*VtTcAV*Vt*(VdA/Vd)=TcA*VtTcAV=Tpr2AV+TinAV=ToutAV+Tpo1AV

Accordingly, the following expression is obtained.YV/VdV≧(Tf1+Tf2+Tf3+(P+2)*(a+b)*Ts+2*a*Ts−(Tpr1AV+Tpr2AV+Tpo1AV+TpoAV2)*VdA/Vd)*Vt/(Vt−VdA)

Where the reading of the after-recorded audio data and the reading ofthe AVM data are performed in one cycle of reproduction, thereproduction condition of the video data is as follows.YV′/VdV≧TcA+TcAV+(a+b)*TsYV′=TcAV*Vt*(VdV/Vd)

Accordingly, the following expression is obtained.Y′/Vd≧((a+b)*Ts)*Vt/(Vt−Vd−VdA)

The reproduction condition is less strict than the recording condition.

As a second specific example, a method for recording and a method forreproduction in the case where the audio data is after-recorded in arecording area which is distanced from the recording area of the AVMdata will be described with reference to FIGS. 20, 21 and 22.

FIG. 20 shows an arrangement of the AVM data and data forafter-recording data on a disc. The AVM data is continuously recorded(recording areas 200, 201, 202, 203, 204 and 205). For after-recording,the data is recorded in recording areas distanced from the AVM data(recording areas 206, 207, 208 and 209).

The reproduction start position is set in the recording area 200, andthe after-recording start positions for audio data and the correspondingvideo data are set in the recording areas 201 and 206, respectively. Theafter-recording termination positions are set in the recording areas 204and 209, and the reproduction termination position is set in therecording area 205.

FIG. 21 shows the order of the recording areas shown in FIG. 20 to beaccessed for after-recording. As described above, data is after-recordedin correspondence with the AVM data which is immediately previous to theAVM data which has just been read. In the previous specific example, therecording area of the AVM data and the recording area forafter-recording are close to each other, and thus the access timebetween these areas is short. In the case of FIG. 21, the access time islonger and the sizes required for the recording areas are larger.However, the arrangement of the recording areas for after-recording hasflexibility. Therefore, data can be after-recorded in a new area,without overwriting the previously after-recorded data, i.e., whileleaving the previously after-recorded data.

Hereinafter, a simultaneous recording and reproduction condition forrealizing after-recording in the order of the recording areas to beaccessed shown in FIG. 21 will be discussed.

Here, Ta1, Ta2, Tai and Taj (i and j each represent the number assignedto the data in the order of address) each represent an access timebetween corresponding areas which is determined based on the accessperformance of the drive. Each access time is close to the full seektime.

The simultaneous recording and reproduction condition for video datawith after-recording is as follows.Y/Vd≧Tpr1AV+2*TcAV+Ta1+TinA+(P−1)*(TcAV+TcA+Taj+Tai)+Ta2+TcAV+Ta3+TcA+Ta4+Tpo2AV+(P+1)*(a+b)*Ts+3*a*TsY=(Tpr1AV+(P+2)*TcAV+Tpo2AV)*VtTinAV*Vt*(VdA/Vd)=TinA*VtToutAV*Vt*(VdA/Vd)=ToutA*VtTcAV*Vt*(VdA/Vd)=TcA*VtTcAV=Tpr2AV+TinAV=ToutAV+Tpo1AV

The label “repeated P times” in FIG. 21 means that, for example, in thecase of P=3, AVM2, A1, AVM3, A2, AVM4 and A3 exist in the range of Pnumber of continuous areas, where 2≦j≦P. Accordingly, the followingexpression is obtained.Y/Vd≧Ta1+Ta2+(P−1)*(Taj+Tai)+Ta3+Ta4+(P+1)*(a+b)*Ts+3*a*Ts−(Tpr1AV+Tpr2AV+ToutAV+Tpo1AV+Tpo2AV)*VdA/Vd)*Vt/(Vt−Vd−VdA)

Regarding one cycle of after-recording in which the AVMj+1 is read, Ajis accessed, the data is recorded in Aj, and AVMj+2 is accessed, thefollowing expressions are obtained.Y′/Vd≧TcAV+Taj+TcA+Tai+(a+b)*TsY′=TcAV*Vt

Accordingly, the following expression is obtained.Y′/Vd≧(Taj+Tai+(a+b)*Ts)*Vt/(Vt−Vd−VdA)

In consideration of the section from the reproduction start position toTai, the following expressions are obtained.Y″/Vd≧Tpr1AV+2*TcAV+Ta1+TinA+Tai+3*a*Ts+b*TsY″=(Tpr1AV+2*TcAV)*Vt

Accordingly, the following expression is obtained.Y″/Vd≧(Ta1+TinA+Tai+3*a*Ts+b*Ts)*Vt/(Vt−Vd)

When the three expressions in which the left side is Y/Vd, Y′/Vd andY″/Vd are all fulfilled, after-recording is made possible.

FIG. 22 shows the order of the recording areas to be accessed forreproducing data after after-recording. For reproduction, an access timeis required since the after-recorded data is distanced from therecording area of the AVM data. The condition for reproducing the videodata with after-recording is as follows.YV/VdV≧(Tpr1AV+Ta1+TinA+Ta2+TcV+P*(TcA+Taj+TcAV+Taj)+Ta3+ToutA+Ta4+TcAV+Tpo2AV+(P+2)*(a+b)*Ts+2*a*Ts)YV=(Tpr1AV+Tpr2AV+TinAV+P*TcAV+TcAV+Tpo2AV)*Vt*(VdV/Vd)

The condition for reproducing the after-recorded audio data is asfollows.YA/VdA≧(Tpr1AV+Ta1+TinA+Ta2+TcV+P*(TcA+Taj+TcAV+Taj)+Ta3+ToutA+Ta4+TcAV+Tpo2AV+(P+2)*(a+b)*Ts+2*a*Ts)YA=(Tpr1AV+Tpr2AV+Tpo1AV+Tpo2AV)*Vt*(VdA/Vd)+(TinA+P*TcA+ToutA)*VtTinAV*Vt*(VdA/Vd)=TinA*VtToutAV*Vt*(VdA/Vd)=ToutA*VtTcAV*Vt*(VdA/Vd)=TcA*VtTcAV=Tpr2AV+TinAV=ToutAV+Tpo1AV

Accordingly, the following expression is obtained.YV/VdV≧(Ta1+Ta2+2*P*Taj+Ta3+Ta4+(P+2)*(a+b)*Ts+2*a*Ts−(Tpr1AV+Tpr2AV+ToutAV+Tpo1AV+Tpo2AV)*VdA/Vd)*Vt/(Vt−Vd−VdA)

The condition regarding the video data for the section from thereproduction start position to Ta2 is as follows.(Tpr1AV*Vt*(VdV/Vd))/VdV≧(Tpr1AV+Ta1+TinA+Ta2+(a+b)*Ts)

Accordingly, the following expression is obtained.(Tpr1AV*Vt*(VdV/Vd))/VdV≧(TinAV+Ta1+Ta2+(a+b)*Ts)*Vt/(Vt−Vd)

The condition regarding the video data from the preroll to immediatelybefore AVMj is as follows.YV′/VdV≧(Tpr1AV+Ta1+TinA+Ta2+TcAV+Taj+TcA+Taj+2*(a+b)*Ts)YV′=(Tpr1AV+TcAV)*Vt*(VdV/Vd)

Accordingly, the following expression is obtained.YV′/VdV≧(Ta1+Ta2+2*Taj+2*(a+b)*Ts+TinA−Tpr1A)*Vt/(Vt−Vd−VdA)

The after-recording is different from recording in that in the case ofafter-recording, after the corresponding audio data is read, the AVMdata is read. However, one cycle of after-recording and one cycle ofreading Aj and AVMj are different from each other merely in Taj. Whenall the access times represented by Taj are the same between one cycleof after-recording and one cycle of reading Aj and AVMj, the conditionsfor after-recording and for recording are the same.

Next, as a third specific example, a method for recording and a methodfor reproduction in the case where audio data and video data are encodedand recorded in different areas, and audio data to be after-recorded isalso recorded in a recording area distanced from the video data will bedescribed with reference to FIGS. 23, 24 and 25.

FIG. 23 shows an arrangement of the video data, the audio data, and thedata for after-recording on a disc. The video data and the audio dataare recorded alternately in different recording areas at a prescribedperiod. (The recording areas of the video data are recording areas 210,212, 214, 216, 218 and 220. The recording areas of the audio data arerecording areas 211, 213, 215, 217, 219 and 221. The data forafter-recording is recorded in different recording areas from theseareas, i.e., recording areas 222, 223, 224 and 225).

The reproduction start positions for the audio data and the video dataare respectively set in the recording areas 211 and 210, and theafter-recording start positions for audio data and video data arerespectively set in the recording areas 213 and 212. The after-recordingtermination positions are set in the recording areas 219 and 218, andthe reproduction termination positions are set in the recording areas221 and 220. The after-recording start position for the data forafter-recording is further set in the recording area 222, and theafter-recording termination position for the data for after-recording isfurther set in the recording area 225.

As described above, during after-recording, data is reproduced from thereproduction start position until the reproduction termination positionin the recording areas 210 through 221. Thus, new audio data is added tothe audio data Ai which is recorded from the after-recording startposition to the after-recording termination position. The new data isrecorded in the new recording areas 222 through 225. In this case, theaudio data is after-recorded while reproducing the two pieces of realtime data, i.e., the audio data and the video data which have alreadybeen recorded.

FIG. 24 shows the order of the recording areas shown in FIG. 23 to beaccessed for after-recording, and also shows the reading time from therecording areas and recording time or access time to the recordingareas. As described above, data is after-recorded in correspondence withthe video data which is immediately previous to the video data which hasjust been read. In the previous, first specific example, the video dataand the audio data are recorded together as AVM data and thus there isno access time necessary between the video data and the audio data. Inthis example, the video data and the audio data are recorded separately,and thus an access time therebetween is necessary. However, thearrangement of recording areas for audio data has flexibility.Therefore, audio data can be recorded in a new area, without overwritingthe previously recorded audio data, i.e., while leaving the previouslyrecorded audio data. Similarly, after-recording can be performed aplurality of times.

Hereinafter, a simultaneous recording and reproduction condition forrealizing after-recording in the order of the recording areas to beaccessed shown in FIG. 24 will be discussed. The simultaneous recordingand reproduction condition for video data with after-recording is asfollows.YV/VdV≧Tpr1A+Tpr1V+Tf1+2*(TcA+TcV+2Tfj)+2*Taj+TinA+(P−1)*(TcV+2*TcA+Tfj+2*Taji)+TcA+Tfj+TcV+Taj+TcA+Taj+Tpo2A+Tf2+Tpo2V+(P+1)*(a+b)*Ts+3*a*Ts

The label “repeated P times” in FIG. 24 means that, for example, in thecase of P=3, A2, V2, B1, A3, V3, B2, A4, V4 and B3 exist in the range ofP number of continuous areas, where 2≦j≦P. Accordingly, the followingexpression is obtained.YV=(Tpr1V+(P+2)*TcV+Tpo2V)*VtTinV*VdA=TinA*VdVToutV*VdA=ToutA*VdVTcV*VdA=TcA*VdVTcV=Tpr2V+TinV=ToutV+Tpo1VTcA=Tpr2A+TinA=ToutA+Tpo1A

Accordingly, the following expression is obtained.YV/VdV≧(Tf1+Tf2+(P+5)*Tfj+(2*P+2)Taj+(P+1)*(a+b)*Ts+3*a*Ts−Tpr1A−Tpri2A−Tout A−Tpo1A−Tpo2A)*Vt/(Vt−VdV−2*VdA)

In consideration of one cycle of after-recording in which Aj+1 is read,Vj+1 is accessed, Vj+1 is read, Bj is accessed, data is recorded in Bj,and Aj+2 is accessed, the following expressions are obtained.YV′/VdV≧TcA+Tfj+TcV+2*Taj+TcA+(a+2*b)*Ts YV′=TcV*Vt

Accordingly, the following expression is obtained.Y′/Vd≧(Tfj+2*Taj+(a+2*b)*Ts)*Vt/(Vt−VdV−2*VdA)

In consideration of the section from the reproduction start position toimmediately before Vj+1, the following expressions are obtained.YV″/VdV≧Tpr1A+Tpr1V+Tf1+2*(TcA+TcV+2Tfj)+2*Taj+TinA+TcA+Tfj+3*a*Ts+5*b*TsYV″=(Tpr1V+2*TcV)*Vt

Accordingly, the following expression is obtained.YV″/Vd≧(TinA+TcA+2*Taj+Tf1+5*Tfj+3*a*Ts+5*b*Ts)*Vt/(Vt−VdV−VdA)

By determining the sizes of the recording areas of the audio data, videodata, and data for after-recording such that the sizes fulfill the abovethree expressions, simultaneous recording and reproduction is madepossible.

In the above specific examples, the data for after-recording is recordedin a recording area distanced from the audio data and the video data.Alternatively, the video data, audio data and data for after-recordingmay be recorded in this order by turns. In this case, the recordingareas for the audio data and data for after-recording are determined inadvance when the video data is recorded. Since the recording areas aredetermined in advance, the recording areas cannot be easily used forother purposes when no after-recording is performed. However, an accesstime for data for after-recording is shortened, and thus thesimultaneous recording and reproduction condition is alleviated.

FIG. 25 shows the order of the recording areas to be accessed forreproducing data after after-recording. For recording, Bj needs to berecorded after Aj is read. The condition for reproduction is less strictthan the condition for recording since access to Aj and reading of Ajare not necessary.

INDUSTRIAL APPLICABILITY

With an information recording medium according to the present invention,a recording operation and a reproduction operation are switched to eachother in accordance with the amounts of data accumulated in the buffermemories. Therefore, the recording buffer is controlled to be kept closeto empty, and the reproduction buffer is controlled to be kept close tofull. Accordingly, even in a situation where data cannot be read by thepickup for a prescribed period of time, simultaneous recording andreproduction can be performed stably. Since the recording operation andthe reproduction operation are switched at an appropriate timing,simultaneous recording and reproduction can be realized with a smallbuffer memory capacity. In the case where data is assigned such that theareas in which data is to be recorded has at least the minimum sizerequired for four access operations, simultaneous recording andreproduction can be performed without fail even for a disc having datarecorded by another apparatus.

By setting the optimal simultaneous recording and reproduction conditionutilizing different transfer rates of the data to be recorded and thedata to be reproduced, data having a low transfer rate can be recordedin a smaller recording area, which improves the utilization efficiencyof the disc.

1. A method for simultaneously recording and reproducing a plurality ofpieces of real time data in accordance with a simultaneous recording andreproduction model, wherein the simultaneous recording and reproductionmodel includes a pickup P for accessing an area on an informationrecording medium, an encoding module EMi for encoding real time data Di,a recording buffer WBi for accumulating the encoded real time data Di, areproduction buffer RBj for accumulating real time data Dj read from theinformation recording medium, and a decoding module DMj for decoding thereal time data Dj accumulated in the reproduction buffer RBj, the methodcomprising the steps of: searching for an unassigned area in a volumespace in the information recording medium and assigning at least oneunassigned area in the volume space as an area Ai in which the real timedata Di is to be recorded; executing a recording operation Wi forrecording the real time data Di accumulated in the recording buffer WBiin the area Ai; executing a reproduction operation Rj for reading thereal time data Dj from an area Aj having the real time data Dj recordedtherein; determining whether the real time data Di has been recorded upto an end of one of at least one area assigned as the area Ai or not inthe recording operation Wi; when the real time data Di is determined tohave been recorded up to the end, switching the recording operation Wito another recording operation Wi or a reproduction operation Rj; andwhen the real time data Di is determined not to have been recorded up tothe end, continuing the recording operation Wi; and determining whetherthe real time data Dj has been reproduced up to an end of one of atleast one area assigned as the area Aj or not in the reproductionoperation Rj; when the real time data Dj is determined to have beenreproduced up to the end, switching the reproduction operation Rj toanother reproduction operation Rj or a recording operation Wi; and whenthe real time data Dj is determined not to have been reproduced up tothe end, continuing the reproduction operation Rj; wherein: each of theat least one area assigned as the area Ai is structured to fulfill acondition that the real time data Di, which is accumulated in therecording buffer WBi during n number of access operations accompanyingswitching between the recording operation and the reproductionoperation, (m−1) number of recording operations and (n−m) number ofreproduction operations, can be recorded by one recording operation;each of the at least one area assigned as the area Aj is structured tofulfill a condition that the real time data Dj, which is accumulated inthe reproduction buffer RBj during one reproduction operation, can beconsumed during n number of access operations accompanying switchingbetween the reproduction operation and the recording operation, (n−m−1)number of reproduction operations and m number of recording operations;and i is any integer of 1 or greater and m or less, j is any integer of(m+1) or greater and n or less, m is any integer which fulfills m<n andis 1 or greater, and n is any integer of 2 or greater which representsthe number of the plurality of pieces of real time data for simultaneousrecording and reproduction.
 2. A method according to claim 1, wherein:each of the at least one area assigned as the area Ai has a size of Yi,and each of the at least one area assigned as the area Aj has a size ofYj;Yi=(n×Ta×Vt×Vdi)÷{Vt−(Vd1+Vd2+ . . . +Vdn)};Yj=(n×Ta×Vt×Vdj)÷{Vt−(Vd1+Vd2+ . . . +Vdn)}; Ta is an access timerequired for the pickup P to access between an innermost area and anoutermost area of the information recording medium; Vt is a datatransfer rate between the pickup P and the recording buffer WBi, andalso a data transfer rate between the pickup P and the reproductionbuffer RBj; Vdi is a data transfer rate between the encoding module EMiand the recording buffer WBi; and Vdj is a data transfer rate betweenthe decoding module DMj and the reproduction buffer RBj.
 3. A methodaccording to claim 1, further comprising the steps of estimating anaccess time required for the pickup P to access from an area Ak to anarea Al where k and 1 are each any integer of 1 or greater and n orless, and k≠1.
 4. A method according to claim 3, wherein: each of the atleast one area assigned as the area Ai has a size of Y, and each of theat least one area assigned as the area Aj has a size of Y;Y={(T1+ . . . +Tn)×Vt×Vd}÷(Vt−n×Vd); Tk is the access time; Vt is a datatransfer rate between the pickup P and the recording buffer WBi, andalso a data transfer rate between the pickup P and the reproductionbuffer RBj; and Vd is a data transfer rate between the encoding moduleEMi and the recording buffer WBi, and also a data transfer rate betweenthe decoding module DMj and the reproduction buffer RBj, for all valuesof i and j.
 5. A method according to claim 3, wherein: each of the atleast one area assigned as the area Ai has a size of Yi, and each of theat least one area assigned as the area Aj has a size of Yj;Yi={(T1+ . . . +Tn)×Vt×Vdi}÷{Vt−(Vd1+Vd2+ . . . +Vdn)};Yj={(T1+ . . . +Tn)×Vt×Vdj}÷{Vt−(Vd1+Vd2+ . . . +Vdn)}; Tk is the accesstime; Vt is a data transfer rate between the pickup P and the recordingbuffer WBi, and also a data transfer rate between the pickup P and thereproduction buffer RBj; Vdi is a data transfer rate between theencoding module EMi and the recording buffer WBi; and Vdj is a datatransfer rate between the decoding module DMj and the reproductionbuffer RBj.
 6. A method according to claim 1, wherein the area Ai andthe area Aj are provided in an outer portion of the informationrecording medium, for all values of i and for all values of j.
 7. Aninformation recording and reproduction apparatus for simultaneouslyrecording and reproducing a plurality of pieces of real time data inaccordance with a simultaneous recording and reproduction model, whereinthe simultaneous recording and reproduction model includes a pickup Pfor accessing an area on an information recording medium, an encodingmodule EMi for encoding real time data Di, a recording buffer WBi foraccumulating the encoded real time data Di, a reproduction buffer RBjfor accumulating real time data Dj read from the information recordingmedium, and a decoding module DMj for decoding the real time data Djaccumulated in the reproduction buffer RBj, the information recordingand reproduction apparatus comprising: means for searching for anunassigned area in a volume space in the information recording mediumand assigning at least one unassigned area in the volume space as anarea Ai in which the real time data Di is to be recorded; means forexecuting a recording operation Wi for recording the real time data Diaccumulated in the recording buffer WBi in the area Ai; means forexecuting a reproduction operation Rj for reading the real time data Djfrom an area Aj having the real time data Dj recorded therein; means fordetermining whether the recording buffer WBi is empty or not while therecording operation Wi is being executed; when the recording buffer WBiis determined to be empty, switching the recording operation Wi toanother recording operation Wi or a reproduction operation Rj; and whenthe recording buffer WBi is determined not to be empty, continuing therecording operation Wi; and means for determining whether thereproduction buffer RBj is full or not while the reproduction operationRj is being executed; when the reproduction buffer RBj is determined tobe full, switching the reproduction operation Rj to another reproductionoperation Rj or a recording operation Wi; and when the reproductionbuffer RBj is determined not to be full, continuing the reproductionoperation Rj; wherein: each of the at least one area assigned as thearea Ai is structured to fulfill a condition that the recording bufferWBi can be made empty by at most one access operation and at most tworecording operations; each of at least one area assigned as the area Ajis structured to fulfill a condition that the reproduction buffer RBjcan be made full by at most one access operation and at most tworeproduction operations; and i is any integer of 1 or greater and m orless, j is any integer of (m+1) or greater and n or less, m is anyinteger which fulfills m<n and is 1 or greater, and n is any integer of2 or greater which represents the number of the plurality of pieces ofreal time data for simultaneous recording and reproduction.
 8. Aninformation recording and reproduction apparatus for simultaneouslyrecording and reproducing a plurality of pieces of real time data inaccordance with a simultaneous recording and reproduction model, whereinthe simultaneous recording and reproduction model includes a pickup Pfor accessing an area on an information recording medium, an encodingmodule EMi for encoding real time data Di, a recording buffer WBi foraccumulating the encoded real time data Di, a reproduction buffer RBjfor accumulating real time data Dj read from the information recordingmedium, and a decoding module DMj for decoding the real time data Djaccumulated in the reproduction buffer RBj, the information recordingand reproduction apparatus comprising: means for searching for anunassigned area in a volume space in the information recording mediumand assigning at least one unassigned area in the volume space as anarea Ai in which the real time data Di is to be recorded; means forexecuting a recording operation Wi for recording the real time data Diaccumulated in the recording buffer WBi in the area Ai; means forexecuting a reproduction operation Rj for reading the real time data Djfrom an area Aj having the real time data Dj recorded therein; means fordetermining whether the real time data Di has been recorded up to an endof one of at least one area assigned as the area Ai or not in therecording operation Wi; when the real time data Di is determined to havebeen recorded up to the end, switching the recording operation Wi toanother recording operation Wi or a reproduction operation Rj; and whenthe real time data Di is determined not to have been recorded up to theend, continuing the recording operation Wi; and means for determiningwhether the real time data Dj has been reproduced up to an end of one ofat least one area assigned as the area Aj or not in the reproductionoperation Rj; when the real time data Dj is determined to have beenreproduced up to the end, switching the reproduction operation Rj toanother reproduction operation Rj or a recording operation Wi; and whenthe real time data Dj is determined not to have been reproduced up tothe end, continuing the reproduction operation Rj; wherein: each of theat least one area assigned as the area Ai is structured to fulfill acondition that the real time data Di, which is accumulated in therecording buffer WBi during n number of access operations accompanyingswitching between the recording operation and the reproductionoperation, (m−1) number of recording operations and (n−m) number ofreproduction operations, can be recorded by one recording operation;each of the at least one area assigned as the area Aj is structured tofulfill a condition that the real time data Dj, which is accumulated inthe reproduction buffer RBj during one reproduction operation, can beconsumed during n number of access operations accompanying switchingbetween the reproduction operation and the recording operation, (n−m−1)number of reproduction operations and m number of recording operations;and i is any integer of 1 or greater and m or less, j is any integer of(m+1) or greater and n or less, m is any integer which fulfills m<n andis 1 or greater, and n is any integer of 2 or greater which representsthe number of the plurality of pieces of real time data for simultaneousrecording and reproduction.
 9. An information recording medium allowingfor simultaneous recording and reproducing of a plurality of pieces ofreal time data in accordance with a simultaneous recording andreproduction model, wherein: the simultaneous recording and reproductionmodel includes a pickup P for accessing an area on the informationrecording medium, an encoding module EMi for encoding real time data Di,a recording buffer WBi for accumulating the encoded real time data Di, areproduction buffer RBj for accumulating real time data Dj read from theinformation recording medium, and a decoding module DMj for decoding thereal time data Dj accumulated in the reproduction buffer RBj; each of atleast one area assigned as an area Ai in which the real time data Di isto be recorded is structured to fulfill a condition that the real timedata Di, which is accumulated in the recording buffer WBi during nnumber of access operations accompanying switching between the recordingoperation and the reproduction operation, (m−1) number of recordingoperations and (n−m) number of reproduction operations, can be recordedby one recording operation; each of at least one area assigned as anarea Aj having the real time data Dj recorded therein is structured tofulfill a condition that the real time data Dj, which is accumulated inthe reproduction buffer RBj during one reproduction operation, can beconsumed during n number of access operations accompanying switchingbetween the reproduction operation and the recording operation, (n−m−1)number of reproduction operations and m number of recording operations;and i is any integer of 1 or greater and m or less, j is any integer of(m+1) or greater and n or less, m is any integer which fulfills m<n andis 1 or greater, and n is any integer of 2 or greater which representsthe number of the plurality of pieces of real time data for simultaneousrecording and reproduction.
 10. An information recording mediumaccording to claim 9, wherein: each of the at least one area assigned asthe area Ai has a size of Yi, and each of the at least one area assignedas the area Aj has a size of Yj;Yi=(n×Ta×Vt×Vdi)÷{Vt−(Vd1+Vd2+ . . . +Vdn)};Yj=(n×Ta×Vt×Vdj)÷{Vt−(Vd1+Vd2+ . . . +Vdn)}; Ta is an access timerequired for the pickup P to access between an innermost area and anoutermost area of the information recording medium; Vt is a datatransfer rate between the pickup P and the recording buffer WBi, andalso a data transfer rate between the pickup P and the reproductionbuffer RBj; Vdi is a data transfer rate between the encoding module EMiand the recording buffer WBi; and Vdj is a data transfer rate betweenthe decoding module DMj and the reproduction buffer RBj.
 11. Aninformation recording medium according to claim 9, wherein: each of theat least one area assigned as the area Ai has a size of Y, and each ofthe at least one area assigned as the area Aj has a size of Y;Y={(T1+ . . . +Tn)×Vt×Vd}÷(Vt−n×Vd); Tk is an estimated access timerequired for the pickup P to access from an area Ak to an area Al, wherek and 1 are each any integer of 1 or greater and n or less, and k≠1; Vtis a data transfer rate between the pickup P and the recording bufferWBi, and also a data transfer rate between the pickup P and thereproduction buffer RBj; and Vd is a data transfer rate between theencoding module EMi and the recording buffer WBi, and also a datatransfer rate between the decoding module DMj and the reproductionbuffer RBj, for all values of i and j.
 12. An information recordingmedium according to claim 9, wherein: each of the at least one areaassigned as the area Ai has a size of Yi, and each of the at least onearea assigned as the area Aj has a size of Yj;Yi={(T1+ . . . +Tn)×Vt×Vdi}÷{Vt−(Vd1+Vd2+ . . . +Vdn)};Yj={(T1+ . . . +Tn)×Vt×Vdj}÷{Vt−(Vd1+Vd2+ . . . +Vdn)}; Tk is anestimated access time required for the pickup P to access from an areaAk to an area Al, where k and 1 are each any integer of 1 or greater andn or less, and k≠1; Vt is a data transfer rate between the pickup P andthe recording buffer WBi, and also a data transfer rate between thepickup P and the reproduction buffer RBj; Vdi is a data transfer ratebetween the encoding module EMi and the recording buffer WBi; and Vdj isa data transfer rate between the decoding module DMj and thereproduction buffer RBj.
 13. An information recording medium accordingto claim 9, wherein the area Ai and the area Aj are provided in an outerportion of the information recording medium, for all values of i and forall values of j.